If you get caught by a jellyfish, it can be quite painful. To alleviate the pain, you can rub the affected area with high-proof alcohol (e.g. vodka), preferably making a compress.

 

Vodka also helps against the burning of poison ivy. A salt bath also helps against poison ivy and stinging nettle. If the skin has a large rash, it is best to take a full bath in salt water.