When a girl is only thinking about having anal sex.
Yo I was ready to bust a nut in this girl's vag but next thing I know I'm all up in her ass! I got caught up in her posterior motives...
by Teh butt s3x0rs May 03, 2010
Posterior meaning buttocks, the phrase is derived from the phrase "ulterior motives". The phrase refers to a male being phony twords the opposite sex with the intentions of sexual Intercourse.
Seeing a male explaining any of the following to a female could be seen as having Posterior Motives: "I'm different than the other guys", "I love poetry!", "I think you look great with no makeup" "I think you are so unique" ect ect.
by LilBobbySaget September 06, 2013