on shank's pony

On foot; walking. Also seen as "on shanks' pony" or "on shanks's pony." A reference to the shank—the lower leg between the knee and the ankle—and the historical use of ponies or horses for travel. My bicycle fell apart three miles away from home, so I had to go the rest of the way on shank's pony. Unfortunately, with the sedentary lifestyle many lead today, fewer and fewer people go anywhere on shanks' pony.

on Shanks's pony

using your own legs as a means of transport.

Shanks (from the Old English word sceanca , ‘leg bone’) is now used as an informal term for ‘legs’. The original form of the expression was on Shanks's mare .