Supposedly started by a blogger on sarcasticindiefucks.tumblr.
idk-> I don't know
idek-> I don't even know
dek-> Don't even know.
For the linguistically adventurous, it can also be used as a verb.
Also, see the variation on a variation, dec.
I don't even know.
She doesn't know.
They don't know, they have no idea.
I didn't even know!
The TWAT-Team of S-F (Tactical Women's Ass Terrorist)
The guy who likes hentai better than normal anime.
Hobbies: Raping Kakashi's, making pervert comments