Variation of 'kthxbye' - the internet bastardization of "OK, thank you, goodbye".

Generally used with contempt, or for hasty exit. See also - kthxbye
n00b: Hey man whats up? You going out tonight?

l337: Yeah I'm on the way to the club right now kthxbai
by #1 October 25, 2003
Literally "Okay, thanks, bye". Commonly used when short words and phrases are needed, as in when chatting and texting. Can also be used to quickly end a conversation, usually in a rude fashion.
Jane: "Hai John! Sup?"

John: "Nm, gtg, kthxbai."

or

Jane: "Hey John, why won't you talk to me?"

John: "Because. kthxbai."
by avengergirl May 14, 2010
'Kay, thanks, bye.
(Okay, thank you, goodbye.)
A hasty way to tell someone goodbye, especially if you dont' want to talk to them. Also see kthxbye.
Person1: Oh, yeah, you're not really my friend. Kthxbai. *leaves*
Person2: *facepalm*
by your mother.. May 29, 2010
K Thanks goodbye

kthxbai can also be used as an insult to someone, like a n00b or someone you just don't like.
N00b1: omg liek u wana c my fab nu jurnal?
Dude: No, you make me sick n00b Kthxbai
by Gabe Hall June 25, 2005