I don't think the joke would work as well with just any other desirable thing. The joke sets up the scene with two geeks and a sexy woman and there's some amoun

I don't think the joke would work as well with just any other desirable thing. The joke sets up the scene with two geeks and a sexy woman and there's some amount of expectation that the joke is going to be about their relative sex drives or the mathematician only knowing how to have sex in theory or something similarly boring and familiar. It's then somewhat surprising when it turns into a joke about philosophical paradoxes and is therefore funnier with the surprise.