Whatever, I don't know butt-physics.
The correlation between the laughter and the presence or absence of said gluteus maximus must be in there somewhere, right?
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)