It's short for I don't give a fuck.
Jenny:Oh my God!Nick dumped me!
You think to yourself IDGAF,but you say "poor baby" instead.
"Idgaf" is a slang term, short for "I dont give a fuck"
another similar word is "Idgas" meaning "I dont give a shit"
kat: Hey, i took a poop.
joe: uh idgaf...
kat: why???
IDGAF MEANS I DONT GIVE A FUCK.
TETE: GIRL U UGLY ASF U NEED TO GET YOUR FACE DONE
BAD BITCH: BITCH IDGAF WAT U SAY BC U UGLY ASF I CAN PULL MORE NIGGAS THEN U AND THAT PERIODT
Short for "I don't give a fucking shit", is rarely used but used when you're angry as fuk, or has massive boredom because of people constantly bugging you gossiping about a person or just doesn't care about a person's opinion on something.
Mary: Did you know that James slapped a girl in the face because of a argument about games causing violence?
Joey: Mary, IDGAFS about that.