Top Definition
During a fart, when air is compressed between the grundle and a hard surface- the air erupts to the nearest exit, usually out the front of the crotch. It is thunderous, not just for the thunderous noise it makes, but also because of the unsettling direction of the blow.
I had a serious thunder grundle in math class, i think i sprained my taint.
by ceegee2 January 23, 2013

Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from daily@urbandictionary.com. We'll never spam you.

×