noun
Vulgar slang for female genitalia. Very crude; avoid in polite conversation.
あの子、まんこ見せてくれたんだぜ。
That girl showed me her pussy.
noun, noun or participle which takes 'suru'
Vulgar slang for sexual intercourse. Often used with する.
昨日、彼女とまんこした。
I fucked my girlfriend yesterday.