Chap
Can be used as a substitute for any word in the English Language.
"I would chap that" - literally they would fornicate with said person

"Chap off" a form of suggestion, potentially chap means "fuck" here but each users intention may vary.

"I'm chapped" your guess is as good as mine. Potentially they could be tired, or extremely drunk. Perhaps even laughing, or upset. It honestly is very confusing.

"What you chapping"? - Often used to ask how someone is doing, substitute of "what you saying"?