An abbreviation for the phrase "if you care."
Person: Idc, iyc.
Shorthand for In Your Corner.
Used to tip you off when the person you're disagreeing with is in your corner. Useful when you're arguing while drunk or stoned and your buddy wants to keep you from being embarrassed.
Dude, shut up, he's IYC.
Stop saying stupid shit, he's IYC, he knows what he's talking about.