The smell that exists when a bunch of teenage boys sleep and eat in the same room for over 24 hours without showering. If you experience the ass muffin smell you are advised to internally combust, because your life is over.
zomg that hax! He UnleasHED a nasty ass muffin smell!
A small creature that crawls into your anal cavity and proceeds to create muffins at his leisure. Mind you, these are no ordinary muffins. Once created, there is only one way for the muffins to exit your rear.