Shower Quack 

The act of farting in the shower as water muffles the noise causing it to sound somewhat like Donald Duck laughing.

I took a shower earlier and farted, sounded like Donald duck laughing, a total Shower Quack

Shower Quack by StolenDignity March 22, 2012

Shower Quack 

When a fart is conducted in the shower and the water running over the anus makes it sound like a duck quacking.

Friend 1: "I farted in the shower earlier and it sounded like Donald Duck laughing."

Friend 2: "SHOWER QUACK!"

Shower Quack by Unwept, the Lone Magpie March 23, 2012