The girl in the playground

I like to laugh so much even if someone is very serious with something  I can still laugh. But one day every one was so stressed I don't even know why, So I go and ask every single one what has happened no one answers and everyone take me to the serious mode. I walk around my village and saw one girl will playing in the playground so I go and talk to her and she see my serious she play a lot of joke but only one of the joke  that can make me laugh. So I walk home and I told that joke to every.