physics humor

Not all that funny to me, but I think it would make Rodney laugh. John of course would pretend he didn't think it was funny just so Rodney would keep talking at him, trying to explain why it was so funny and getting all annoyed and pissy when John keeps saying "I get it, Rodney, but it's just not funny." John just loves to wind Rodney up.

Oh yeah, the comic: http://xkcd.com/c182.html