A mouthbreathing illiterate moron's mishearing and subsequent misspelling or mispronunciation of the word "comeuppance." The combination of "cum" and "muffins" adds hilarity to the usage of the term, as the word is typically placed in the syntax as an object to be received, as a result of karma, by a person perceived to have committed a wrong.
1. Because of actions taken, fate will balance and hand some "bad luck" to the individual, thus somewhat being the revenge of fate
2. An ideal embracing the saying "What goes around, comes around"
Guy: "Wow the weather here is so beautiful! It's a shame you're stuck in Canada and freezing your ass off."
Guy 2: "Just you wait, you'll get your comupins !!"
Revenge or payback. Used as a noun to sound cooler than just saying revenge. Said by Michael and Logan on Zoey 101 when they were trying to get revenge on Vince Blake.