He is an ordinary looking skunk, wearing an air helmet like Sandy does. He has black eyes, gray eyelids, a black nose, and black and white fur.
Plankton tries to use this skunk to prevent customers from going to the Krusty Krab. The reason he sprays his huge spray of stink is because Plankton puts a bumblebee into Mr. Stinky's air helmet. The customers thought that he was a cat, but when he sprays the Krusty Krab, all of the customers, Squidward, SpongeBob, and Mr. Krabs frantically leave the Krusty Krab due to the stink. Plankton used Stinky as a distraction so he could steal the formula, but he couldn't steal it because there were several safes. Mr. Stinky is removed from the restaurant by the HAZMAT Unit and sent away back up to the surface in a basket lifted up by balloons, only for the little number of balloons to bring him back down toward Bikini Bottom, causing the people to run away.