Very Nice example
A new vacuum cleaner salesman knocked on the door on the first house of the street. A tall lady answered the door...
Before she could speak, the enthusiastic salesman barged into the living room and opened a big black plastic bag and poured all the cow droppings onto the carpet.
"Madam, if I cannot clean this up with the use of this new powerful Vacuum cleaner, I will EAT all this dung!" exclaimed the eager salesman.
"Do you need chilly sauce or ketchup with that" asked the lady.
The bewildered salesman asked, "Why, madam?"
"There's no electricity in the house..." said the lady.
MORAL: Gather all requirements and resources before working on any project and committing to the client...!!!