Heavy cream ass can be defined as an insult, or term to describe someone who is heavy and has cream in their ass. It could also be used as a sexual term for Cumming in someone.
Guy 1: You see that girl over there?
Guy 2: Your crush Tory?
Guy 1: we're not just crushes now, we've taken things much higher
Guy 2: Oh yeah?
Guy1: I gave her a massive Heavy cream ass last night~
Guy 2: Nice!