Lima Beans are an edible legume. They are physically seen in a cameo appearance in the episode "Krabby Land," and are also mentioned in an earlier episode, "Fools in April," when SpongeBob says, "Even the part about the lima beans and the car chase?"
The beans are contained in a can; the label of said can is colored red with a white square on it. Inside the square, the words "LiMA BEANS" are written in black; the words are stacked and there is an illustration of three Lima beans between the two words.
In "Krabby Land," Mr. Krabs puts together a cheap playground (a.k.a. Krabby Land). He also gets SpongeBob to go through torturous tasks to entertain the kids, including being force-fed lima beans. Krabs passes out coloring books, and says that the kids who turn in their coloring books get to meet "Krabby the Clown". Krabby the Clown turns out to be Mr. Krabs in a colorful tie, and a blue painted tomato on his nose. The tough guy holding the lima beans in the picture punishes Mr. Krabs by tying him up to two pieces of wood, and feeding him lima beans.