I'd give Ollie's 7/10.
What about this one?
It was a perfectly normal day in Bank of London when an old, tiny woman went up to one of the counters and said:
"Can you call for some security personel and make them help me get some money out of the car? I want to put them in my safe deposit box."
"It's not busy here today, and I can't call on security for that. Let me help you instead", the woman behind the counter answered.
"No thanks. I'm asking for help to carry three million, seven hundred on fifty-two thousand pounds out of my car, and into my safe deposit box".
The service woman was shocked, and called for the bank manager himself, who in turn called for two security guards, who had to go several times from her trunk to the vaults, due to the incredible amount of notes, packed in small plastic bags. While the bank manager and the lady were watching the guards, he asked her:
"Excuse me, I see you have retired, and even though I haven't, I know that you can't get these sums from the pension. So how do you earn all this money?"
"It's easy. All the big money lies in bets nowadays. For example, I hereby challenge you to a bet: I bet two hundred thousand pounds on that your testicles are square!"
"Square?", the bank manager thought. "This woman is nuts. But it's £200,000 to me, and she can obviously afford it."
So he accepted the bet.
"Alright, then. Meet me at my lawyer's office at 12 o'clock tomorrow, we'll check then. Here's the address".
The bank manager took several showers that night, to really ensure himself that his nuts were shaped as they were meant to. And of course, they were. But then, why had the woman seemed so confident?
Next day, he left early for lunch, and at 12 o'clock he stood in an office together with the old lady and her lawyer.
"Let's get over with it, then", said the woman. "Or are you backing out?"
"I'm not", the bank manager replied. He felt a bit uneasy as he undressed, even more when the old lady started touching his "family jewels".
After less than 30 seconds, she stood up and said: "Round. No doubt. I guess I was wrong, then".
"Of course you were. Did you ever think something else? But... why is your lawyer beating his head against the wall?"
"Of, that", she chuckled. "Nothing to worry about, I just bet £750,000 with him that today, at twelve o'clock, I would stand in his office, holding the balls of the manager of the Bank of London in my hands."