Derogatory term for a homosexual person, the metaphor being of course about anal sex, hence the position of the zipper (in the rear). Can be used either to talk about the person itself (see first example) or to point out a characteristic of said person (see second example)
First example :

Steve : Dude, check out the rearside zipper at the bar ! Gotta tell Andy, he needs to get some ass fast, the pillow partition is barely keeping him at bay these days...
Dave : Word, man, word.

Second example :

Kyle : Oh bro, I just spotted a major queer man !
Brian : Where ? Jesus ! The dude does have a major rearside zipper indeed !
Kyle : You know it !
(Homophobic and highly unethical high-five)
by Klisstoriss February 17, 2012
Get the rearside zipper mug.