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.
by ceegee2 January 23, 2013
Get the Thunder Grundlemug. When you have a big veiny triumph bastard of a cock and it gets so hard and railing a chick from behind so fucking hard Zeus himself comes down from the clouds and gives you a round of appaulse
by Super fagalicious January 19, 2017
Get the cock thundermug. by Tinyradman May 26, 2018
Get the Thunder Malletmug. by noah p m. October 17, 2008
Get the thunder sticksmug. by Paul January 20, 2005
Get the Johnny Thundersmug. by Tim November 7, 2004
Get the Mud Thundermug. a girl with perfect hips and thighs and knows how to rock a bikini. Usually has the best body out and goes perfect with abs. Thigh gaps arent even needed if you have thunder thighs, your basically perfect already! be careful not to judge people by this, and dont use it against them.
thunder thighs are the opposite to fat so dont make it out to be
thunder thighs are the opposite to fat so dont make it out to be
by biggesthottayevahh November 26, 2013
Get the thunder thighsmug.