Having done many hours of "Requirements Gathering" as they call it in Project Management, I can appreciate this one. Ok, sure it's a "Blonde Joke", but I've had clients in a professional setting that were just like this.
The key is to make sure you really do understand what the person on the other side is saying.
A blonde, wanting to earn some money, decided to hire herself out as a handyman-type and started canvassing a wealthy neighborhood.
She went to the front door of the first house and asked the owner if he had any jobs for her to do. “Well, you can paint my porch. How much will you charge?”
The blonde said, “How about 50 dollars?” The man agreed and told her that the paint and ladders that she might need were in the garage.
The man’s wife, inside the house, heard the conversation and said to her husband, “Does she realize that the porch goes all the way around the house?”
The man replied, “She should. She was standing on the porch.”
A short time later, the blonde came to the door to collect her money.
“You’re finished already?” he asked.
“Yes,” the blonde answered, “and I had paint left over, so I gave it two coats.“
Impressed, the man reached in his pocket for the $50.
“And by the way,” the blonde added, “that’s not a Porch, it’s a Ferrari.”