All jokes aside, please don't piss on someone who was stung on the face by a box jellyfish. All you are likely to do is give them an eye infection. You should treat them the same way that you would treat a bee sting. First, make sure that there are no tentacles or other jellyfish parts stuck to the affected area. If there are, don't try to remove them with your hands. Scrape them off with a towel or anything else that will prevent skin-to-skin contact. Rinse the area with seawater. There is an entire ocean's worth of it. Then call 911 because some folks have a very bad reaction to deadly neurotoxins. If you are confident that it is not an emergency situation involving anaphylactic shock treat the affected area like you would any other skin irritation (such as poison ivy). A paste of baking soda or some calamine lotion will do. Do not bother pissing on them. Just don't do it. However, there is some evidence that urine will help with your athlete's foot, but you have to walk around with feet that smell like piss so you judge for yourself if the juice is worth the squeeze.