Beating your girlfriend and or wife.
Drish: Hey where has Tom been
Robably: He went to jail for thumpin on his meat. I called the cops so she didn't end up hurt too bad.
Drish: Oh no! I hope she is ok.
To have one of your nuts hit the clitoris during intercourse.
Bro, I was banging this girl doggy style last night with such elegance that it had me nut thumpin her so hard she stored my name as thumper in her phone.