Is it normal i found this video funny but informative?

http://youtu.be/9W91kDPjDmU I don't mean ha-ha funny but just the fact someone is waiting so they could grab peoples butt. I mean what the fuck? That is the craziest thing I have ever heard. I also know what this feels like since in school everyone did this. They also have this joke "Its not rape if you yell surprise". Which no one takes super serious. Which this is not really rape is sexual harassment but people do this crap.