It's not uncommon to be on the receiving end of jellyfish's sting when you go for a swim in the sea—but what is it that provides that numb feeling you get as a result? And should you really pee on it to make it better?

In actual fact, the jellyfish shoots out a neurotoxic venom that's enough to paralyse its prey but only hurt humans. And as for peeing on it? Turns out that's more of an excuse for your friends to cover you in their urine than provide any real help. Typical. [YouTube]