Krust is a toothpaste that comes in a teal tube and has a red cap. The tube depicts the product's name in red letters inside a yellow circle.
Role in the episode
SpongeBob attempts to open this bottle of toothpaste. After this fails, he hits it with a wrench and the cap flies off. He then walks out and trips over the cap. This causes his eye to hit the wrench, giving him a "shiner."
It is a parody of the real-life toothpaste brand Crest.