When your cock isn't up to it and it resembles a slug but you try to stuff it in anyway and the receiving hole is tight. Like the opening coin slot on a money box.
"Hey Colin did you get laid last night?"
"Yeah bruv, me cock wasn't interested though so it was like sticking a slug in a money box"
"Yeah bruv, me cock wasn't interested though so it was like sticking a slug in a money box"
by Bixadon December 15, 2017
Get the slug in a money box mug.