When someone is filled up with a bodily fluid to the point of overflowing or leakage. Usually used as an insult to someone who is acting like a hoe, sket and/or whore. Mostly used to comment on someones mother, if they like to sleep around with the boys.
person 1: your mums waterlogged mate.
person 2: nah, i know who my father is. my mother didn't sleep around my good sir.
other example.
Person 1: Calfreezy and The Burnt Chip are waterlogged
Crowd: MMM yes, I agree