The floating shopping list is a shopping list that appears in the episode "One Krabs Trash."
The floating shopping list is a piece of lined three-ring binder paper used as a shopping list. On one side is a list of three grocery ingredients in order from top to bottom: milk, eggs, and cheese. On the other side is the ghost that Mr. Krabs had drawn. The paper is hooked onto a fishing rod.
The floating shopping list has previously been used as a shopping list, but later on, it has been used for Mr. Krabs to draw a ghost on the opposite side, which is shown to be blank. Mr. Krabs then hooks it onto his fishing rod and attempts to scare SpongeBob into giving the Soda Drinking Hat to him.
When he is scaring him with the piece of paper, SpongeBob is scared by the words on the "floating shopping list," as he describes it. Mr. Krabs then notices this and swiftly changes the side of the paper to show a ghost instead.