When someone has taken a pee and it has overflowed the buttsack.

no defenition i think it sounds funny

When an angry wife chops off her husbands ballsack and staples it to his butthole.

Buttsack

/butsak/ (noun)

Buttsack is a noun meaning wrinkly butt or flabby cheeks.

If it’s cold enough, a mans nutsack goes so far upwards it falls out of a mans anus

A lump on someone's but that keeps growing then turns into a pimple. Sometimes it's just fun to call people that name too.

so basically its like a ballsack but one nut is in the front under the shaft and the other one is in the back towards the anus. also called a buttnut. if you were to shut your legs the buttsack nut would be visible from the back while the normal nut is in the front still.