Belly button lint is an accumulation of fluffy clothing fibres and, to a lesser extent, dead skin cells in the navel cavity.
Belly button lint was a flavour of Bertie Bott's Every Flavour Beans. Harry Potter personally found this flavour revolting. Navel Fluff Buster was a wizarding product designed to clean lint from the belly button.
Behind the scenes
- The line of dialogue that mentions this particular flavour of Bertie Bott's Beans was intended to be used in the Game Boy Color version of Harry Potter and the Philosopher's Stone. However, this dialogue went unused in the final game, though it still appears in the game's ROM.
- Harry Potter and the Philosopher's Stone (video game) (Cut from final game)