If you get stung by hydra, anemones, or corals, you should pour vinegar on the wound to activate all the stinging cells (nematocysts). Otherwise, the wound will heal over them and continue to irritate you for years. It happened to me with a scratch from some hard coral. The wound itched me almost to insanity for YEARS after the initial event. I literally had to cut the wound open with a razor blade to pour vinegar into it. The itching stopped immediately and hasn't returned since.
I've also heard of peeing on jellyfish stings (same stinging nematocysts), but I prefer vinegar myself
I think that's for emergency situations like if you were stung away from home. But it accomplishes the same result: fire the stingers so they're "used up".
I've also heard of peeing on jellyfish stings (same stinging nematocysts), but I prefer vinegar myself