if you're a girl it's when you go to a party and drink alot and then you meet some guy and you go and fool around
if you're a guy its when you meet a girl and take advantage of her situation...
her being drunk, emotionaly down...anything
"Man that girl was so used, that guy fucked her up."
"Last Saurday I went to this party and i drank soo much and then I met this guy names Cory and he tried to get in my pants and i couldnt stop him because i was soo drunk. He used me"