A sexier way of saying c'mon.
Often used in sleazy rock songs.

I would like to revise my original definition of Sh'mon as I now believe that it may be incorrect. My reason for thinking this is that I recently saw the TV chef Jamie Oliver greeting his friends with the phrase on Jamie's School Dinners, so I now believe it to be some kind of English slang greeting rather than a sleazy variation of "c'mon". If anyone from England understands the exact meaning or origin of the phrase, please elaborate.