An ankle shark is a term (noun) for a cat when it is stalking around your ankles, often brushing against your leg. Also used as a verb, ankle sharking, to describe the activity itself.

When a cat (or other pet) stalks or winds around your ankles, weaving in and out, often brushing against your legs with its body and tail. Used as a compound verb. Also see the noun form: ankle shark.

when a cat is walking in circles around your feet, usually waiting for food and/or attention, and occasionally rubs up against your ankles/legs with it's face or rear end. Motion is reminiscent of sharks circling their prey.