The Problem with 89

Alright, listen up, numbskull. The joke is a play on words. "89" sounds like "ate-nine." Get it? The joke implies a sexual act, suggesting that "89" is upset because they "blew" someone (performed oral sex) and now they're owed a favor. It's like math and sex had a baby, and that baby is you... 'cause you don't get it. Sad.