A fork of Rural Dictionary
This is what occurs when someone shits themself while wearing a diaper. This is most commonly executed by babies and senior citizens and can happen accidentally or intentionally. It absolutely must be a poop of high liquidity so that it covers the exact region normally covered by a bikini bottom.
When I brought that old lady home from the dive bar I was pleasantly surprised that she had her shitkini on. Once I took off her diaper I didn't even need to lube up to slip m'dick right on in.