(Pronounced "Kay-Thanks" - One word) Thanking someone for doing something that you aren't really giving them the option to do in the first place. This is always said in a sarcastic tone and there is usually a prolonged emphasis on the "s."
Honey, I know you have the flu, but please go outside and shovel the 7 feet of snow we just got last night. Kthanks.
Signalls the ending of a conversation. Usual follows a distinct point made. k=okay thanx=thankyou bai=goodbye. Kthanxbai replaces the need for "thats the end of it".
Jeremy: Im so much cooler than you.
Andrew: No your not i am much cooler that you idiot.
Jeremy: how rude
Andrew: Just shut up you noob im cooler kthanxbai