It is widely believed that urine is an effective way to treat a jellyfish sting. Not only is urinating on your wound not effective, but it could actually make it worse. So if you ever get stung dont let your friend pee on you, no matter how much they insist.
This is most likely a myth started in order to keep kids from swallowing their gum. Yes, the chewing base cant be broken down by the digestive system, but that just means it passes through completely intact and at the same rate as anything else.