usually used as an insult or joke.
man1: dude you ugly!
man2: yo mama!
Yo Mama is a reference to yo mama jokes meaning when you say yo mama that means you think their mom is ugly fat or stupid
hey look its Yo Mama.
verb, abbreviation of "volume yo-yo" the act of lowering the volume during television commercials then raising it again when the regular program resumes.
"I hate watching TV with my dad, he's hard of hearing so we have to turn it way up, but he hates commercials and wants them muted, so we have to play vo-yo the whole time."