Andy wants to pull a prank on William by hiding in his closet and turning off his TV. William finds out and was gonna burn Andy's phone, but Andy had swapped phones with William, so he unknowingly burns his own phone. William then goes berserk and fights with Andy, trashing the kitchen in the process.
This is the second time that William's buttocks were shown, the first being WILLIAM REFUSES TO SEE THE SPECIAL DOCTOR!!!