11 Common Movie Tropes That Would Actually Ruin Your Life

2. Peeing On A Jellyfish Sting

The pain of a jellyfish sting is most often caused by nematocysts that lodge into the skin and discharge poison. This is bad enough without a slightly-too-enthusiastic do-gooder using you like a urinal.

The worst thing you can do for a jellyfish sting is to rinse it in fresh water (well, actually, the worst thing you can do is continue to rub the jellyfish all over your body but YKWIM). The change to the balance of concentrations of salts inside and out of the nematocysts will likely activate the stinging once more.

The idea behind the urine remedy is probably based in the fact that urine, unlike fresh water, contains salts and electrolytes. But, do you know what else contains salts and electrolytes? The sea. You know, the thing you're probably no more that 10 feet away from.

Urine is way more like freshwater than saltwater and will likely end up causing the nematocysts to fire. The best thing to wash a sting with is seawater, but the most important part of treatment is removing the little barbs by scraping the sting site with a razor, credit card or piece of shell.