Flounder
A flounder is the act of pushing one's buttocks together while standing and defecating, resulting in two brown smears forming on each of the buttocks. These smears each are flat, brown, and circular, much like the shape of the flounder fish. Floundering is preferably done in the shower, so that one can simply rinse the flounders off when done, and no one has to know about it.
Example:
Matt told me about how he gave himself a flounder last night, and went into way too much detail. Gross!
Matt told me about how he gave himself a flounder last night, and went into way too much detail. Gross!