Urine: Jellyfish sting cure?

Years ago from watching a Friends episode with my dad, I came under the impression that peeing on a jellyfish sting would take the pain away. In the episode Monica, Joey and Chandler were at the beach where Monica got stung. Joey remembered hearing that peeing on a sting take the pain away, and in the end pressured Chandler into peeing on Monica to "cure" her sting. Apparently it turned out fine for that trio, but does peeing on a jellyfish sting really help?

A travel site called UpTake posted an article on a first aid guide when getting stung by a jellyfish, and does not mention urine at all.

About talks about various things that can and should not be used to treat a jellyfish sting. When being stung by a box jellyfish using vinegar on the wound is the best solution. Vinegar neutralizes the nematocysts so they cannot shoot out venom. When vinegar is not available using salt water is next best, while fresh water should be avoided because it causes the nematoxysts to inject the venom. They go on to mention urine, since urine is mostly fresh water it can actually make the sting worse. It depends a lot on diet, hydration, and other conditions on how effective it will be.

While vinegar helps remove pain from box jellyfish stings, it can increase pain of stings from Portuguese Men of War and other physalia stings.

UpTake's first aid guide explains how one should remove any remaining stingers with gloves from affected area. Instructs people to use vinegar if they know it is a box jelly, but that the best bet is to just use saltwater to wash the area. There may be some tiny tentacles left in the affected area, so UpTake recommends spreading shaving cream and "shaving" it off with a credit card edge. Drinking Benadryl to avoid allergic reactions and seeking medical attention are also very important.

Bottom line, it is unwise to pee on anyones jellyfish sting, as you will have a natural pain relief from the ocean water you were most likely just in to have gotten stung. Keeping vinegar and shaving cream in your beach bag wouldn't hurt either.