1. Rasta way of saying "Yea, man" (Translation into mid-west jargon is "You Betcha")
2. An enlightened, or enthusiastic agreement, especially if by stating the obvious there is a greater signifigance that is left unsaid.
1)Mega chamon, i have just won a million pounds
2) So we will go out to the pub tonight yeah? Cha mon!
3) You mean im actually dead,in hell, and i'm destined to spen eternity in agony? Gigga-Anti-cha mon!