Le Squish is an alter-ego of SpongeBob in the episode "Demolition Doofus." SpongeBob received the name from Captain Lutefisk, after being a very tiny size, but able to compete in the derby.
Le Squish rides in a very tiny boatmobile with the number two, and he wears a sock.
Role in episode
When Mrs. Puff puts SpongeBob in the derby, Captain Lutefisk is unsure. After seeing what he can do, Lutefisk puts his sock over SpongeBob and inserts him into the derby.