Haha let's try a cute one for now... While I'm thinking of one...
There was a couple who had a child was lost in a city. They wanted to rent a room and they saw a poster saying room rental. They knocked on the door and an old man came out.
The couple told him they wanted to rent a room. He surveyed them for a while and told them he will not rent the room to people bringing their children. So sadly , they left.
However, the child suddenly stopped and went back and knocked on the door again. Curious, the couple waited and see what was happening. Soon, the Old man came out and the child said something to him. The old man suddenly laughed and allowed them to stay for the night.
What did the child say to him???