How do you make someone faint?

i just did it and it totally worked , it was like being on drugs for 20 seconds.

crouch against a wall with your knees to your chest, take 15 huge breaths, stand up holding your breath until you fall :) when you fall you wont feel a thing but when you wake up you might have injuries.

(another guy)

you do know that making yourself faint causes the death of brain cells right? And you just have to hold your breath, it stops oxygen to your brain and you pass out. (lack of O2 causes brain death)