Their marriage was on the rocks and he began spending most of his time out carousing. One evening he came home quite drunk with a sheep tucked under one arm. As he staggered into the bedroom his wife looked up and demanded, "why the hell did you bring that filthy animal in my house?!"
The man drunkenly replied, "Here's the fat pig that I have sex with when you won't put out."
His wife snorted and said, "If you weren't so stupid, you'd realize that's a sheep."
He said, "If you weren't so stupid, you'd realize I wasn't talking to you."