It is a boat where Mr. Krabs was the head chef. Little is known about it other than that Mr. Krabs worked there and that it presumably sells horrible food.
Mr. Krabs was asked by Squidward if he served on a restaurant called the S.S. Gourmet which he said he did. He later reveals that he mistook Squidward for saying S.S. Diarrhea and that he cleaned the bathrooms of the S.S. Gourmet.