This is most likely based on a bit from his 70's era stand-up comedy by the same title. It appears on his now rare "Comedy is Not Pretty" album.
Cruel Shoes was also the title of Steve Martin's first book, a collection of short stories and essays, released in 1977. The title 'Cruel Shoes' is of one of the essays included, a satirical short-short story about a woman in a shoe store.