Quacking farts
Quacking farts are flatulence which sounds like a duck.
Dr. F. wondered if the student had a duck up his ass due to the quacking farts he heard.
quack fart
When you cut a fart while taking a shower with water running through your ass crack and it makes the sound of a duck quack. Quack farts often smell worse than regular farts.
I let a quack fart slip while my girlfriend was in the shower with me and she bolted.