Water Weasel Share definition Flag When a man, postmortem, usually as a result of heart failure, has fluid built up (edema) in the genitals that makes arterial embalming difficult. Look at the water weasel on this guy. The hospital must have been pumpin' his ass full of fluids. Water Weasel by Morty_the_Mortician September 16, 2020 Get the Water Weasel mug.