to redefine the features of someones face by brute physical force from one's fist. Also can be used in place of "beating the shit out of", "demolishing", "kicking ass", etc.
Present tense: I am going to mop up on any naysayers who oppose the crooked design of my concept car.
Past tense: The naysayers were mopped up on when they called out the marginal concept design.
A man that likes to pick up women on the rebound bec that's the best he can do. Typically invites women in bad relationships out to lunch or dinner and scores some cheap sex. This type of guy generally plays the role of caring friend and can never say no to a girl in need. Never fall for this kind of guy. His self esteem is dependent on how much he is mopping up.