It is a long and light pink novelty toy tongue. There's a tag on it that says "Novelty Toy." The word "Novelty" is dark purple, and the word "Toy" is light orange.
Role in the episode
Sandy grabbed it and was going to pour hot sauce on it, thinking it was SpongeBob's real tongue. After SpongeBob surrenders and Sandy drinks the hot sauce, SpongeBob reveals it was a Novelty Toy Tongue and uses it to trap Sandy and spin her and was going to karate chop her before she karate chops him.