The girls are preparing cookies for a bake sale, but Cleo is late. She arrives just before the bell, unashamed of her lack of commitment and proud of the new giant mutant octopus polish adorning her fingernails. Her friends aren't amused and tell her to get to work immediately. Cleo does so, if warily of what damage baking may do to her nails. However, due to her lateness, the bell goes when she's barely even touched an unbaked cookie. The group leaves to continue baking later.
What no one noticed is that a bit of Cleo's nail polish stuck with the cookie dough she touched. It becomes sentient, absorbing the other cookie dough and growing in size and hunger rapidly. Its first victim is Mr. Hackington, who sneaks into the kitchen area to steal a cookie. Next, the girls enter. The first thing they notice is that all the cookies are gone and the second that there is a cookie dough monster on the loose. They flee the room screaming.
The boys in the corridor, waiting in line to be the first bake sale customers, try to fight the creature, but even Deuce's gorgon stare doesn't stop it. Almost all of them are subsequently eaten by the cookie dough monster, but when it's Heath's turn to become a snack, the monster's weakness is found: heat. Heath quickly bakes the monster to death, after which all his friends and Mr. Hackington emerge alive from the cookie spill. Frankie spots the nail polish bit that caused all the trouble, revealing that Cleo is to blame. When Headless Headmistress Bloodgood arrives and orders the mess to be cleaned up, everyone agrees that to be Cleo's job. Cleo takes solace in the fact that at least the cookie spill contains chocolate chips.
- The webisode is a light homage to the 1958 horror movie The Blob.
- This is one of the three webisodes first released as an extra on the "13 Wishes" DVD on October 8, 2013. As its "Ghouls Rule"-predecessors, it will likely be released in the regular line-up some months into 2014.