Farmer's Poultry Compliment

Alright, listen up, you big dummy! This joke is funny because "cock" has two meanings. It means a male chicken, like a rooster, which the farmer is clearly talking about. But it's also a rude word for a man's private part. So, the joke is in the naughty sound of a farmer complimenting someone's "cock" while innocently referring to the bird. See, you're always thinking about the wrong 'cock' first, aren't you?