This is an interesting question, and there's a serious, positive answer.
(1) You stand upright, between two friends. One is facing you, and the other is behind you, looking forward towards you.
They are there for safety reasons, to make sure that when you faint, you don't fall and injure yourself, and each has his/her arms under yours and over each other's shoulder, braced, to catch you.
You place your arms over theirs, so their arms are completely safely supporting you, under your armpits, and relax.
(2) Now, with them overseeing the process, you carefully take in, -and then breathe out, about 10 - 15 very deep breaths, as deep as you can., (hyperventilation
(3) Finally, - you close you mouth, nose, eyes, and ears (!) and try AS HARD AS YOU CAN to breathe out, putting on pressure by compressing the diaphragm .( Well, - you're actually doing a version of the Valsava sequence)...
You're applying maximum internal pulmonary pressure
. And within split seconds you'll faint.
(3) Your two friends will catch you, and prevent you falling. Then you'll come to, and won't even know you've fainted. ... honest. They'll tell you, but it's so fast, so easy, and so safe that you will never know it's happened. If you want convincing, get a fourth person to take short video of it.
Don't do it too often because it's so weird, and there are no statistics on its safety.