A disgusting, sloppy vagina with sludge-like excretions (mucus, afterbirth, sperm, feces, etc). Likely accompanied by very foul odor.
A sludgina is what you might expect a wompus
or a cheap hooker to have.
So I hooked up with this chick at the bar, but then I found out she had a sludgina!
Gross dude, I can smell her sludgina from here!
Chuckle my sludgina!