Making a soufflé
When you and your bro have to take a dump at the same time but there is only one toilet bowl so you both straddle it and sit face-to-face. The volume of poop is so great that it rises above the water level and resembles a cooked soufflé.
“Dave just bought a home and Ted suggested making a soufflé in his brand new bathroom because the other toilets were occupied.”