FOREWARN: This post is ironic, as always.
Some made up terms I use:
* Self-care-ness: the realisation of self-worth and self-love.
* Homodisgrace: substitute for homophobia because it is not a phobia.
* Gender blindness: ignorance of gender knowledge.
Previously, I have written a thoughtless piece on coming out, and the notification signals the 500 views that it has.  
Wow. That was too much for a piece of nonsense, and I have better in-depth insights to share with you on this. So I will start with the universal definition of coming out, the act of telling your gender, or as Vietnamese likes you put it, r e a l gender to somebody. You might have seen Ingrid Nilson coming out, or you just have no respect for legends.  Coming out is a large part of gay culture. It can be compared to a turning point, like the meeting point in the below line graph. 
The coming out line graph. (BlackNeedleIllustration)
Closeted queer people, often showing no gender clues whatsoever, suffering from mental strains and self-denigrating thoughts, will one day reveal their true self and adopt their dreamed-of life. Coming out, thus, is a dramatic twist between depression and euphoria, a confirmation of self-concept. One, in the recognition of self-care-ness, can let the strains from their surrounding be overshadowed by this newly-found empowerment. Hence its name coming out, 101.
As waves of social changes is hitting all nations, except for some, coming out is becoming more casual, with entire TV shows dedicated to queer people (mostly nice-looking gay males) in the closet. What we watch in each region is also affected. Youth from countries like Russia has their videos shared and re-shared zillion of times among queer community in America for its heart-touching substance. Vietnam is starting to rethink about our communities with positivity, with the general consensus moving from "these faggot" to "I generally don't care" or "They are normal people". Coming out, in this post only, is referring to Vietnamese coming out-ness because I am thoroughly conscious that this is a Vietnamese platform and it feels absolutely not good to click on this with the intention to help yourself but turns out you get absolutely no help at all duh. 
Alright then.

1. Gay-straight discussion in Vietnam.

The concept of gender in Vietnam is more or less rigid, with influencers knowing very basic and overly-simplified aspects of gender. Thus, the gay - straight dynamics are foreseeable and cringeworthy considering the media depiction, as opposed to the real-life casualtyness. Take the new episode of Trắng for example. The title itself is a clickbait, yet, put it aside, the show goes on with three homosexual guests and paired with three straight counterparts.

Pair one, which I call shylets, consists of one feminine boy and a casual, straight boy with a fair amount of edginess. Close enough to the gay - straight spectrum of the past.
Pair two, which I call city boys, is a specimen of the gay - straight dynamic typically seen in high schools or real life where gay people aren't stoned to death. The gay bro is enthusiastically pushing hidden flirts, while the straight guy, having no intention to respond because that wouldn't be so straight, smile awkwardly because of his humor.  
Pair three, which I call the cool progressives, is having chill vibes all over the place. The straight guy is calm, formal and mature-ish, in contrast to the robust, happy-go-lucky gay guy. There is no weirdness in their conversation, as both guys know that this is nothing weird rather than knowing that they are not supposed to act weird. 
This is gay meeting straight realness. The relationship (not what you think) dynamic between a straight dude and their gay friends is always a Joel Barish - Clementine thing. Barish, the straight guy, is indifferent, air-conditioned and rough, whereas their counterparts talk with extra enthusiasm and emotions-run-free-ness. Plus, it is clear that although the straight guy in Pair two doesn't like boys, he does like the flirts that his gay friend gives out. *whisper* because they give him confidence *end whisper*.

2. Why they talk that way.

Long, long time ago, when gays and straights were inhabitants of two hemispheres, they did not know much about each other. Freedom had not been protected, so there are absolutely zero reasons for gay people in the past to showcase their sexuality, or they might do so but without the conception of being gay.
Then everything came and go, bad things, and then everything is modernised and flourishing in the 2000s. People in the early 2000s know more about the surrounding world than just themselves, and gay people start to form conceptions about themselves mostly based on media outlets, yet their language is still straight-made. They internalised the cruel "oh môi" or "b(p)ê đê" joke from straight people as a self-identification tool to relate to themselves and their peers. Unity among queer groups was not seen, yet, in contrast, straight unions was too successful in oppressing queers. Media depictions were written by, from the view of and for straight people, thus HIV is generally understood as Homosexually Infected Virus.
So whoever grows up among the 2000s, even queer youth, has very introductory concepts about genders and sexes, let alone homosexuality. Yet, changes kicked in starting with bibliographies and literary works such as "Không Lạc Loài" or "Bóng". A vague concept has been formed, as more a tolerant view is somewhere on the horizon. But only now that we have witnessed a Renaissance of queer culture. People empathize more with heart-wrenching videos of coming out gay stories. The consensus among straight people, as I said, now shifted to "Do what you wanna" and "You are normal". Even then though, I identified four major sub-groups, organized from homodisgrace to okay dudes. There can always be people lying between these groups, as well as some case where you don't need to worry about (violent homodisgracers or, on the other hand, an ally expert on Gender Studies):
The Vietnamese homodisgrace - ally spectrum. @TheBlackNeedle.
With that being said, the following will discuss how to deal with these people. 

2. Coming out.

Different groups need different strategies to deal with. Find out what category the person you are coming out to belongs to, and follow my instruction:
1. Group 1: You cannot do this alone.
-Group one can be your parents colleague or close teachers. You yourself cannot dissolve their lifelong prejudice about genders, thus coming out would seem very risky. 
-Building a straight persona is the conventional method of gay people, yet concurrently they, the dogmatic ones, must be exposed to gay-ness from various sources. It can be a parental support group (not available in small cities yet), news stories, films or your real queer friends. Straight allies are also good supporters.
-Declaring your relationship with them is toxic and sensitizing them to your traumas is also effective, as it breaks the barrier between you and them.
-Then, you have to find a common ground by restating your relationship, whether it is parents-offspring or boss-employee, and direct them to a common goal, which is your happiness, work efficiency and a healthier relationship. 
Don't wait for the last straw, plan for it. 
2. Group 2: be icy.
Straight guys' attempts to steal gay humor are always bouncing back and forth around four corners: I AM ACTUALLY NOT GAY AND THIS MEME IS MADE TO DECLARE THAT, hey my straight friend you are gay, the butt sex and the sword fight. The end. But, contrary to that, there are a myriad of dank aspects that can only be discovered by pure gay unicorns. Rét Đít Bê Đê Fanpage provides an excellent example: 
The dank, precious, queer humor that straight guys could only dream of.
So cheap memes are un-extravagant. How to clap back?
In the face of cheap memes, efforts to reply with knowledge of genders only work when you are straight because no one will assume:
- you know that much about gender,
- you will clap back,
- you are an ally of LGBTQ+ community and now the spotlight is yours.
But I will assume that you are not straight, and some cheap meme guys get in your way. It is not wise to respond by anger, because that will feed the troll even more. My suggested resolution is to plan a bite-back joke beforehand. Yet, again, I will assume that you are not a nerd like me, so other recommendations are:
- clapping back with your own experience, which is the precious thing that straight guys don't have.  
- laughing until they feel uncomfortable.
If you attempt to come out to these not-so-serious guys, make sure to introduce them to real (self-denigrating) gay humor. That is the only humor, in its highest form.
3. Group 3: just give them a reason.
- These people are open-minded enough to stress the importance of seeing gay peers as normal, so telling them to be more open-minded would be counterproductive.
- Instead, a reason should be given. If they already have their reasons in mind, it's time to showcase and impress them with your gay power.
- Don't push, but shows them the tender side of gayness, or a gay people in the field which they can resonate with.
- About the "ew don't kiss" thing, I think sometimes it just feels weird to watch a kiss, regardless of the kissers. Some straight guys do follow gay love stories and they tell me that it doesn't feel weird at all, seeing kisses as a proof of love. They, as pure Asians, hate public kisses. 
4. Group 4: meh :)
- Inundate them with love so that they can resist your love but secretly like the love that you give deep inside because it makes them feel loved.
- They can convince others to accept you, so use them wisely. I mean don't use them, but let them help you.

3. It's not that important.

I did not come out to my family. Dads are always our biggest challenges, right? Mine too. Whenever I think of come out, I always try to use my rational mind first: Is telling them about my gender really make my life better, or is there a revenging attempt driving my decision? Most of queer pals wait for the moment to come. However, these moments of extreme sentiments are also our most vulnerable ones. Make sure you are strong when you come out. What will I lose after this? I can loose my education and my fundings forever. What do I really aim for? Is that just recognition or acceptance? Is this even necessary? What are our reasons for coming out? If the other person does not use their rationality too, you should drive them back to that lane.

In many cases it is not necessary. Coming out can get you killed, stoned, traumatized, alienated. Until gay people whole-heartedly stand up together, then coming out remains a hard, individual choice. But it's yours to make.

Some interesting reports, not necessarily related to the topic:
Kim Den.