hooking up

if you're "hooking up" with someone that means you've hooked up more then once and have been for a while
to "hook up" with someone means you made out and probably went farther (especially if you were both drunk)

We've been hooking up for a while now.

Dude, I can't believe she hooked up with him. What was she thinking?!
She was drunk.

20👍 48👎