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1.
A-nil Mon-stir. Phrase describing a woman slut who loves to have the cock placed in her asshole.
Catherine Zeta Jones took my cock in her ass like a champion. Shes an Anal Monster.
by WackBag December 03, 2005
 
2.
A female who offers anal sex or has had anal sex with more than one partner.

"Anal Monster" refers only to a female, and does not apply to a female that has only had anal sex once.
"Tara is wild, yo, she wanted to have mad anal"
"That girl is an anal monster, yo"
by mynameisraquel September 24, 2011