look up any word, like fap:
 
1.
The act of having vigorous sexual intercourse.
"Yo, I seen your girl yipin' in the car with some dude."
by johnny bolas July 03, 2009
 
2.
People yelling and typing their yells online. Mostly done in chat rooms. Also known as Yahoo Trippin.
I went into a chat room the other night and they were yipin at each other.

"Calm down, why are you yipin?"
by King Titus May 11, 2006