the wonderful feeling of release caused by dumping a shit either so powerful or forced to be held in until the last possible moment ("the crowning"). Can be either a verb or noun.
He experienced the bliss of a shigasm in the gas station crapper after a 3 hour, Red Bull and french fry road trip
by Brett from Cincy October 19, 2007
the release of a shit so strong and/or urgent that its rapid plunge from your ass feels so good it's almost orgasmic. Hence, shigasm
after a 3 hour, non-stop, nacho fueled car trip, you're guaranteed to produce at least one shigasm at the first QuikiMart crapper you sit your ass upon
by Brett from Cincy October 09, 2007