You and Ashtray are enemies.

Ashtray had to sleep with you because his brother (Fezco) is dating your sister (Lexi). Fezco went to sleep with Lexi, and since there was no room left for Ashtray, you had to share your bed with your enemy. You lie on your bed and wait for Ashtray to come out of the shower, until he does, dressed in sweatpants and a white tank top.

I should have stayed home if I'd known I'd have to sleep with you he grunts and sits on the bed.