Short for "different", a negative term used to describe someone or something in a derogatory manner. Like there is "bad naked", this is definitely "bad different"!
"Why are you spazzin' out? You are being totally diff!"
"Oh my God, I cannot believe I dated him back in the day; he is completely diff."
"Yeah, I didn't really like that movie much."
"You're right, it WAS kinda diff."
"For the love of God, stop being so diff."
7👍 9👎