Re:What the hell? (Score 2, Informative)

That was in the eipsode where Homer and Marge were spicing up their love life by getting it on in public places. Through some turn of circumstances, they wound up naked in the basket of a hot air baloon in a used-car lot manned by Gil. They took off in the baloon and somehow Homer ended up hanging naked from a rope. They came up on the Crystal Cathedrial (yes, there really is one - one of those TV preacher types built it) and as everyone was looking up, Homer hit the side, making his bare butt squeak accross the glass.