This term is usually associated with online
games. The term is used in the event a player describes a situation in which the outcome was unbelievable, unlikely, or amazing. Player(A) then describes the event to his friend, player(
B), who was not there to witness the event, which to him sounds unbelievable. In which
case, player(
B)in disbelief says, "Screenshots or it didn't happen."
Player(A): LOLWTFOMG!11!!cos(0)
1!!!! HAHAHAHAH, I just one shotted a paladin through his nub shield.
Player(
B): Screenshots or it didn't happen!
Player(A): HAHAHLOLOMGWTF!!1!!!cos(0)!1!! I just
shot my tube from The Hotel across the
map and killed player(C) at the Gatehouse on Karkand in BF2 without knowing where he was.
Player(
B): Screenshots or it didn't happen!
Player(A): Here you go, lol pwnd.
Player(C): NO WAI!!