Generally, the worst thing that could happen to your testicles during a swim is shrinkage.

However, anyone who dares take a dip in Lake Lou Yaeger risks a testicular fate even more embarrassing and far more painful.

Last month, a fisherman reeled in what was initially thought to be a piranha from the waters of the Illinois lake. Upon further inspection, the fish with human-like teeth was actually a pacu. In Papua New Guinea, the pacu is known as a “ball cutter” for its habit of biting off the testicles of local fisherman and then leaving them to bleed to death from their grievous wound.

Since the first pacu was caught there have been reports of at least one other pacu — which can weigh up to 55 pounds — swimming about. It is believed the fish had been aquarium pets and were illegally dumped into the lake.

While lake superintendent Jim Caldwell conceded the pacu’s scary reputation, he doesn’t think that they pose much of a real risk, and continues to swim the lake and allow his young children to do the same. Other visitors to the popular summer swimming spot weren’t so sure about that, and decided they would rather just keep dry and work on their tans.

The good news is that the tropical fish won’t be able to survive Illinois’s cold winter, so by next year all this nuttiness should be over.

Learn more about these nut nibblers in the video below.

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