Mud snail

Thst act of taking a dump on your SO’s back in a swirl (ice cream like) formation. And then allowing it to slid down their back and leave a snail trail.

Boy: damn, kate is a freak.
Other boy: oh really what did she do on her last tinder date this time?

Boy: she mud snailed the poor guy
Other boy: damn you rite she is a freak....what’s her number again???