commonly referred to as RPs, this is another phrase for leggings.

Tights (usu. black) which are worn by a female girl. They fit so tight around her nice arse that it causes certain male boys to think dirty thoughts. Mostly worn by hoes, running chicks, gay men, fat chicks, and girls that have no idea they are showing off their hot legs because they are not hoes, but still dress like they want it in the arse.