no but one time when i was on my trampoline with a friend, he super jumped me (it's where you both come down at the same time, only one of you prepares to jump back up while the other uses his downward force to propell you even highier) anyways, he did that and somehow i twisted in air, and i was in a laying down position... also kinda got thrown from the center to the edge... i came down, first thing that hit was my head hit the steel pipe that goes all the way around the trampoline (where the springs hook) it hurt pretty damn bad.. and if i shook my head, i swear i could feel my brain moving around, and it was making a very weird noise..

edit: oh yeah i forgot to put why i even posted this lol... at first i thought your friend just might have gotten a cuncussion and it wasn't really the weed... but unless the other people had one too, i guess tha'ts not the case.