A man walks into a New York City bank and says he wants to borrow $2,000 for three weeks. The loan officer asks him what kind of collateral he has. The man says "I've got a Rolls Royce -- keep it until the loan is paid off -- here are the keys." The loan officer promptly has the car driven into the bank's underground parking for safe keeping, and gives the man $2,000.
Three weeks later the man comes into the bank, pays back the $2,000 loan, plus $10 interest, and regains possession of the Rolls Royce. The loan officer asks him, "Sir, if I may ask, why would a man who drives a Rolls Royce need to borrow two thousand dollars?"
The man answers, "I had to go to Europe for three weeks, and where else could I store a Rolls Royce for that long for ten dollars?"