US Army slang in common use during the Vietnam War but probably originated during the Korean War. The phrase has multiple meanings which are dependent on the inflexion used and can usually only be determined from the context of the conversation. Four of the commonest are:-
1 No shit? – Are you giving me the facts?
2 No shit! – I am telling you the absolute truth!
3 No shit. – Don’t give me any lies or evasions.
4 No shit? (A question but with an implicit sneer) – Why don’t you carry on stating the obvious, you dumb cocksucker?
“Get your gear together, Charlie’s had his ass kicked and we’ve got 24 hours in Saigon!”
“No shit?”
“No shit!”
One of those miraculous phrases that makes the English language great. Depending on how it is said, can signify either genuine suprise or annoyance with the obvious.
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