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1.
A not-yet popular acronym for the phrase "In case you didn't know". Is sometimes confused for trying to say "Icy Dick"
Me: So ICYDK I am totally tired
Idiot guy: What?!?! Icy dick? Grooss, man!
Me: Go fuck yourself
Idiot guy: I already am *wink*
by Sue Pirnova May 14, 2008
 
2.
Acronym for "in case you didn't know", used when trying to keep long winded posts in internet forums and chat rooms brief.
INCYDK, I am so tired today because I was on the internet all night long.
by I:A:N May 01, 2005