what happens when you hang yourself?!

Well it depends if you just hang suspended or if you drop.

The rope closes the carotid arteries and your jugular veins.
The high pressure on the carotids lead to carotid reflux which reduces heartbeat and causes cardiac arrest.
The airway closes and finally death erection is also common.
This is literally a post-mortem erection, it can also include a release of urine or mucus.

I'm sorry it's so graphic but you did ask. Also sorry about your friend.

When you step off the chair or whatever you were standing on, your neck almost always breaks, so your body actually becomes paralyzed from the neck down as the nerves are now damaged. Then, the knot around your neck strangles you and you suffocate to death. Because your body is paralyzed, you can't do anything to stop it, there's usually no turning back.

Some people are "lucky" and the neck doesn't break, so if they change their minds, they can fix it, or someone might find them and catch them before its too late, safe them and they could be okay, without paralysis (and then get the therapy they need).

Nursing.

Considering that I have not personally tried to hang myself, my guess is that the rope around the windpipe prevents normal breathing. Cutting off air supply causes organs to fail and ultimately, that is what causes death. The body requires oxygen in order to properly work.

Medical Mom

idk i read this somewhere but first the neck breaks (usually) so you go unconsious then you suffocate and die. i think. lol idk

don't do it