A man walks into a bar with an ostrich...

... and orders a shot.

"That'll be $2.40", said barman.
The man pulls out the exact amount, drinks the shot and leaves.
The next day, he walks into the same bar with the same ostrich and orders a meal. Barman comes for the charge of $8.79, so the man pulls out the exact amount and hands it to the barman.
Now, a little intrigued barman asks the man, "How do you do it, sir, that you always have the exact amount needed?". So the man replies:

"I've once fished a gold fish, and she gave me two wishes. My first wish was that whenever i needed to pay, I'd always have the exact amount in my pocket. So when I buy a new mercedes or just some matches, I always have the cash on me."

"Oh", replied barman, "and what about the second wish?"

The man's face got a little frustrated;

"I wanted a chick with tall legs."