Cow: "Hmmm-hmm-hmmm ... (he looks up and reads the sign) 'I know I am a (coe).' ... That doesn't sound right."

(A farmer comes in, grumbling)

Farmer: "Mumble-mumble -- You're not a coe, you're a cow!"

Cow: (brightly) "I get it! Hmmm-hmm-hmm -- 'I (now) I am a cow!'"

Farmer: (walking around, the cow looks confused) "Grumble-grumble-grumble ... Listen -- 'I KNOW I AM A COW.'"

Cow: (smug) "You're not a cow!"