An engineer was walking home from work one day when a frog on the road spoke out to him and said "If you kiss me, I'll turn into a beautiful princess." The engineer picked up the frog, smiled at it, and put it in his pocket.
A couple minutes later, the frog spoke again and said "If you kiss me and turn me into a princess, I'll stay with you for a day." The engineer takes the frog out of his pocket, smiles at it, and returns it to his pocket.
A few minutes after that, the frog speaks to the engineer and says "If you turn me into a princess, I'll stay with you for a day and do whatever you want!" Yet again, the engineer takes the frog out of his pocket, smiles at it, and puts it back in his pocket.
The frog speaks up and says "Look, I've told you I'm a beautiful princess, I'll stay with you for a day, and I'll do whatever you want." The engineer takes the frog out of his pocket and says "Look, I'm an engineer. I don't have time for a girlfriend, but a talking frog, now that's cool!"