A man walked into a bar with a duck on his head. The bartender, surprised, asked the man, "Why do you have a duck on your head?"
The man replied, "Well, I was walking down the street when I heard a voice say ‘Hey you, buddy! Do you want to buy a duck?’ So I looked around and there was a duck standing there. I asked him how much he wanted for the duck, and he said '20 bucks.' So I bought the duck and put him on my head."
The bartender chuckled and said, "That's a funny story, but why is the duck still on your head?"
The man shrugged and said, "Well, now he wants to sell me a monkey."