Often replied with a comeback, "Shit no"
B: No shit??
A: Shit no!
A:Dude your car rides and handles great!
B:Thats exactly what your mom told me last night.
Dude 2 - "No shit."
*Dude 1 tries to think of a comeback*
Dude 1 - "...So, how 'bout them Red Sox?"
First case: often said slowly, emphasizing each word and with "shit" often raised slightly. = "You don't say"
Second case: usually said quickly and without as much emphasis, for you really just want to get on with your life and not listen to this fucktard anymore
a) Are you giving me the facts?
b) I am telling you the absolute truth!