Yummy Bunz is a type of Krabby Patty seen only in the episode "Greasy Buffoons," and they were created by SpongeBob by accident because he dropped them into a puddle of grease by accident. Even though they are not healthy, the Krusty Krab sells them until the Health Inspector comes to see the mess. They were created by soaking Krabby Patty buns in grease for one hour. The new menu item became a hit until Plankton invented Crispity Crunchities to win back the hungry crowd.
When SpongeBob was making a Deluxe Krabby Patty, some buns tipped over and fell into the grease. Mr. Krabs went inside and saw the buns, and served it. When a customer ate it, he enjoyed it, giving Mr. Krabs the idea to make Yummy Bunz.
The name 'Bunz" is spelled with a "z" instead of an "s."
The name 'Yummy Bunz' was also adopted by Viz Media for English version of Japanese anime "Doraemon" which airs on Nick's rival Disney XD. It was used to describe a Japanese confection called 'Dorayaki' which became Doraemon, the main character's, favorite. However, it spelled as 'Yummy Buns' as the name 'Buns' is spelled with an "s" instead of an "z."