Doors:
My neighbour's profession is fitting doors. Just doors.
One day he got a phone call, someone ordering a new door. Question: 'Is it an internal door or an external door?' A long silence, then, 'well, one side of it is external, the other side internal!'

Truthful:
One afternoon on the way home with a car full of kids, they were begging to watch a video once they got home. I explained that dinner would be ready in about half an hour and asked if they would turn of the video then without complaining. "Yes! yes!" - "Promise?" - "Yes!" shouted all but the youngest one, 6 years old. He sat there, thinking deeply, then, "I don't know that I can promise that!"