suprise shit

A suprise shit is when you are doing something that isn't defacating(shitting) and suddenly have the urge to rain down heavenly fury upon the nearest toilet. Every so often it is just a fart. However, i would advise you to take no chances. See also shitting your pants

"Hey mike, what's up?"
"I thought i had to fart yesterday while having sex with my girl, bit it was actually a suprise shit..."
"... You can crash at my place for awhile."