An ass grenade is a shit that has so much force behind it, the shit explodes out of your ass, smashes into the water of the bowl and causes a huge wave of shit-sprinkled water droplets all of over the walls and floor.
This is the shit equivalent of a 500 pound man jumping off of a two story building into a one foot high swimming pool.
The end result leaves shit-shrapnel everywhere!
1. Who in the hell ate the "dog-zilla" from Byron's? Whoever did left a huge ass grenade in the bathroom and should clean it up!