From How I Met Your Mother, Season1 Episode14

Robin: *Who’s up for hanging out?
Ted: Oh I can’t, I’m taking Victoria out for dinner.
Lily: No, no we can’t. It’s our nine – year anniversary.
Robin: Wow, nine years? Your relationship is a fourth grader. Congrats.

From How I Met Your Mother, Season1 Episode14

* Who’s up for: You can use this expression when you ask someone to do something. For example, ‘who’s up for a movie tonight?’