Dupshite is one of the new ways of saying dipshit...dip shit sounds german english of way of saying it. It is said in german Schterken Shise (which obviously means dip shit) duphite has been used commonly around where i am.
1: you are such a pathetic dipshit
2: You dupshite, you know shit all
In chat it's used as STFU. the Real world it is used in many ways to shut people up. People who have been pissed off by a particular may constantly say this phrase. People will say the phrase for fun and people will laugh while the other person is in utter embaresment or they laugh as well.
(chat) Tod_is_1337: i t3h 0\/\/|\|5 j005!
Tod_is_1337: what the fuck does that mean?
(Pissed off) Dickhead: hahahaha!! you suck you suck you suck you suck! i fucked your mum! i fucked her good she squeeled like a..
The pissed off one: SHUT..THE FUCK...UP!!!
(Enjoyment) Daniel: hehe and then the blonde
Steven:Shut the fuck up...you suck