"Knock Knock - Gopher" joke

Knock Knock
Who's there!
Gopher!
Gopher who!
Gopher a long walk off a short pier! Knock Knock
Who's there!
Gopher!
Gopher who!
Gopher your gun, Sheriff! Knock Knock
Who's there!
Gopher!
Gopher who!
Gopher broke!