But if you've just beaten them, then the bruises will be black and blue. They wont turn green until the bruise is healing, which could be several days or weeks. As such, your saying is flawed and wrong. [no]
There should be a law that you're allowed to beatt he crap out of "pranksters" - most of the time they just leave a mess and damage for other people to clean up, costing time and money!
Break their freaking legs, I tell you!