Shane's Mare 

That's the name of the horse you ride when you you don't have a horse. You walk.

Q: How you gettin to town?
A: I'm takin Shane's mare.

Shane's Mare by wotboa July 12, 2012

shank's mare 

Literally, your leg's horse. To go about on your feet. An old expression no one ever uses.

"You look beat! How did you get here?"
"I came all this way on shank's mare!"
"No wonder you're tired!"

shank's mare by Vee Are Are Schee May 22, 2004

ride shank's mare 

To travel by walking.

You taking the bus to school? No I am going to ride shank's mare

ride shank's mare by T Biz Rockahara August 6, 2011