Karate is a Japanese Martial Art that many Japanese are good at. Karate Fighting has been seen in many episodes but its first appearence was in the episode: Tea at the Treedome. In the episode: Karate Choppers karate plays a large part in the episode. SpongeBob likes to call it Kah-Rah-Tae.
Karate has only been seen to be used by the people in Karate Island and also obviously SpongeBob and Sandy; however, in Karate Star, Patrick is shown using it. This could be SpongeBob's favourite source of fitness because weightlifting definitely isn't a sport he likes. Quite a bit of the Karate fighting is in SpongeBob's House and in Sandy's Treedome.
Main article: Karate Gear
Karate Gear is used to protect everybody from hard hits. Everybody uses it. Sandy owns a green, SpongeBob a red, and Patrick a blue.