tiwwaf 

Stands for "this is why we are friends".

Person: I dressed up as pikachu and ran around town screaming "tacos!"

Person 2: TIWWAF

tiwwaf by meowmeowzazzycat February 15, 2012

tiwaf 

Thought It Was A Fart: when you think you are goin to fart so you relaz your cheeks and then realize its not a fart but rather some shit coming out.

Dude i just TIWAF, I better go change my boxers.

tiwaf by BIG ELLAY January 24, 2011