"Krumbly kibble to nibble - it's enough to make you dribble! Can be fed to Mimics in certain dungeons Could be rewarding!"
Mimikibble is a random drop from any of the creatures from the dungeons that feature the Famished Mimik chest and from Cap'n Atcha.
They can be fed to the chest to receive a Mimik Slobber and a chance of receiving a rare item. See Famished Mimik for chest and item locations.