Ejaculation as a result of a nearby friend having intercourse in a body of fresh water, with or without you knowing.
Hey bro I just got stung by your freshwater jellyfish.
While enjoying an afternoon swim in Lake Shasta, out of no where this freshwater jellyfish snuck up on me and stung me right in the face.
Noun;Human male ejaculate floating inside a public shower.
Hey bud, don't step on the endangered fresh water jellyfish swimming in the shower or you'll get a fine.
The male ejaculate left floating in the tub or shower following masturbation, resembling the marine invertebrate. Generally non-poisonous.
"Dude, go ahead and use my shower but I know you haven't been laid for a while. I better not find any fresh-water jellyfish in there later."
"I would never do such a thing, mate. I'm offended you would suggest it... Any baby oil in the medicine cabinet?"