An acronym for the phrase: "Rat In My Poes" which is used to describe how seriously drunk/intoxicated an individual is/was.
The word poes is a common slang term used in South Africa derived from the Afrikaans language meaning: cunt/vagina/pussy.
Jeez bro, I got so RIMP last night.
Wow, those chicks are RIMP!
Dude, how fucking RIMP were you after those drinks we had!