One day, an engineer was crossing a road when a frog called out to him and said, 'If you kiss me, I'll turn into a beautiful princess'.
He bent over, picked up the frog and put it in his pocket.
The frog spoke up again and said, 'If you kiss me and turn me back into a beautiful princess, I will stay with you for one week.'
The engineer took the frog out of his pocket, smiled at it and returned it to the pocket. The frog then cried out, 'If you kiss me and turn me back into a princess, I'll stay with you and do ANYTHING you want.'
Again the engineer took the frog out, smiled at it and put it back into his pocket. Finally, the frog asked, 'What is the matter? I've told you I'm a beautiful princess; I'll stay with you for a week and do anything you want. Why won't you kiss me?'
The engineer said, 'Look. I'm an engineer. I don't have time for a girlfriend, but a talking frog, now that's cool.