A door-to-door salesman knocked on the front door of a home and heard a faint, high-pitched, “Come in.”

He tried the door and it was locked, so he went around to the back door.  He knocked again and heard once more the high-pitched, “Come in.”
 
As he entered the kitchen, a large, mean, snarling Doberman met him.  As he plastered himself against the wall, he called out for help.
 
Again he heard, “Come in.”  He slid down the wall toward the living room to see a parrot in a cage.  He said, “For Pete’s sake, is that all you can say is, come in?”
 
The parrot laughed and said, “Sic him.”