A silent fart that someone sneeeeeks in after someone else has a noisy fart, so that everyone thinks the stink belongs to the first asshole.
Innocent Bystander: Ewww Kate, that fart is rank.
Kate: Nah, that's Dani's ninja fart. She been stinkin it up all day, cuza dat nasty hamachi
she be eatin.
Dani: Eh, heh heh. You caught my ninja.
Innocent Bystander: Ew Dani. Not cool.