Most people don't like taking a poop when it isn't in their own bowl. When they therefore spend a prolonged time away from home, they are likely to refrain from dropping a grumpy until they return home. The drive home therefore becomes more and more excruciating as their body realizes the inevitable glorious release of the little black seal into the porcelain sea... This causes confusion, hysteria and social awkwardness when confronted with unnecessary chit-chat.
Gary: Why'd you take so long to answer your phone!?
Kraig: Geeslike, I cant talk right now, I'm a block away from home and I have the most dangerous homecoming dump already trying to claw its way out of me...
Gary: uuuu... what?
Kraig: ...AAAAaaaaa!!!.... Its... crowning!!