A chocolatemop is when you have diarrhoea and you are about to shit and right before you burst, your partner penetrates your tight arse (with a dick or dildo) and as they’re thrusting you just let it loose.
When you and a few others urinate into a bucket, then soaktwo mops in the urine filled bucket and whack each other with the mops until your opponent either passes out, gets knocked out quits.
This is a slang term invented by the very popular YouTuber "Yikes", and it can mean anything and everything. It doesn't have 1 set definition, and it can mean anything depending on the situation.