Contraction of Ok, thanks, bye.
Used when you want someone to shut up (you're not exactly trying to be polite,) yet it's not considered as an insult like STFU
. Also it can be used when answering a stupid n00b question, or after scolding someone.
I'm not arguing anymore. kthnxbai.
Stop that or I'll ban you. kthnxbai.
^ above isn't as insulting as STFU N00B!