Captain Toad farted while he was going through the sewers since he figured that the stinky fumes emitted from his brapper would help shield him from the smell of the sewer which was actually proving him right since he could be able to breathe through such a reeking place, with him pressing on through since he was fully self aware of the fact that he's been through much worse than even something like a sewer could even dare to compare itself to an ass ripping adventurer like him. "Phew! And I thought I smelled bad; at least when I'm stinky it feels good!"