1. A phrase used to describe the joint in a toe allowing it to bend. Phrase existing to differentiate between the common "knuckle", often only used to describe the joint in a finger.
2. Related to camel toe, when the clitoris is swollen enough to add a protrusion to the common camel toe, resembling that of the a "toe knuckle."
3. An individual whose intelligence compares more closely with that of a rock than a human being.