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1.
I don't know why. used in chat rooms and I.M.ing.
bob: hey did you read that book?
jill: no idky i got it.
by hallway kun August 06, 2007
 
2.
I Don't Know Yet.

Instead of saying IDK (I don't know) to a question, you can say IDKY so your friends at least have some reassurance that you're going to make the effort to answer the question in the future.
Sam: "Hey Tommy, are we on tonight?"

Tommy: "IDKY" (This most likely means that Tommy will eventually tell Sam whether or not they're going to hang out. In this case, Sam has the reassurance that he should get the update at some point that day.)
by scottboy123 March 25, 2010
 
3.
I Don't Know You
Them: Hey!
You: Who are you?
Them: It's me. _____
You: Well, idky
by TextOnTheScreen June 03, 2010