The S.S. Diarrhea is a vehicle that is only mentioned in the episode "Squilliam Returns."
It is a boat where Mr. Krabs is the head chef.
Role in series
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.