chat dude 1: I saw 2pac at work today
chat dude 2: ygbkm!!!
chat dude 1: what!?
chat dude 2: for reals, you're kidding me!! HOAX!!!!
chat dude 1: wtf! we just had beer together last night...!?!
chat dude 2: OH shit in the shithole!!! my chocolate neighbour.
You've Got To Be Fucking Kidding Me, typically uttered in response to anything that is so totally stupid as to be unbelievable.
Note: often pronounced more rapidly as "YiGiTBiFKiM"
Seriously, Congress? You're going to reach an interim deal on the fiscal cliff for now, and then resolve it more permanently in a couple months? YGTBFKM!