Tried it a few times in school, impromptu... didn't go over well with the teachers (or the principal). There was a worn spot on the bench outside the principal's office which conformed to my butt...prolly should have had a little brass plaque made.
Watch the cop laugh: <iframe width="420" height="315" src="//www.youtube.com/embed/-10DgWsSZNc" frameborder="0" allowfullscreen></iframe>