Swedish Icthyologists Tell People Not to Be Alarmed over "Ball-Cutter" Fish

An exotic pacu has been caught in Sweden’s Oresund Sound.  Biologist Henrik Carl is quoted as saying, “The pacu has quite a serious bite… There have been incidents in other countries, such as Papua New Guinea, where some men have had their testicles bitten off.”  Carl acknowledged that such instances are extremely rare.  He confessed that “there’s nothing to worry about” and that Swedish swimmers are more likely to drown than being bitten in a sensitive area by a pacu. - Pete Thomas
Actually a more serious worry than pacus, is earwigs.  With pacus, just wear your swimsuit and you're probably fine  Earwigs will climb up in your ears at night and lay their eggs in your brain.  This is pure scientific fact.  Also bats.  Some people think bats getting tangled up in your hair is just a wives' tale, but it's not.  There've been documented cases of people, especially those with long hair, having bats so inextricably tangled, they had to get their heads entirely shaved.  Bats are almost unbelievably stupid when it comes to hair.  If you must wear your hair long, I suggest you stay in at night or else wear protective headgear, like a stovepipe hat or a baseball helmet.  
As far as sewer-gators, I think New York is finally taking steps to get these under control, but now there are reports of sewer-gator activity in almost every state in the union.  People brought home baby gators as pets and thoughtlessly flushed them down the toilet when they got too big.  Look before you take a seat on the porcelain throne, don't get too close to storm drains, and for God's sake, don't dangle dead chickens over open manholes.  That's just asking for it.  

And Snurks, let's not forget about Snurks.  Remember being a kid, and being terrified to get out of bed at night because there might be something under your bed that bit off toes.  Well, those things are real.  They're called Snurks, and they're prevalent as dust mites only much larger and voracious.  Typically they only go after the toes of naughty children who don't brush their teeth or say their prayers, but you never can tell.  I recommend thoroughly brushing your teeth at night and make sure you pee before you go to bed.  There's nothing worse than lying shivering under the covers, needing to take a pee, but being terrified to get out of bed for fear there's a Snurk under there.