A pimpy promise is a promise made between a prostitute and their pimp.
Pimp: Do you wanna work for me? *holding a wad of $100 notes*
Prostitute: Yeah I guess *looking at the money*
Pimp: Okay but you have to do something first...
Prostitute: *looking confused* what do you want me to do?
Pimp: *Holds out his little finger* Pimpy promise me that you will stay with me forever
Prostitute: Okay
*them both singing together* Pimpy promise, never brake a promise, if you do you have to suck my weener.