A security guard privately hired to walk around a mall, school, concert, event, etc...
Usually rent-a-cops think they are better than everyone else, but usually have very sorry lives. A rent-a-cop usually sees no excitement in his job, so he will bust u for pretty much anything, just for fun
steve: that damn rent-a-cop yelled at me for giving my girlfriend a hug.
dale: oh yeah, that guy hates public displays or affection.
steve: a hug is a public display of affection?
dale: to a rent-a-cop it is!