Jesus is about to raise a girl from the dead. He is about to do the impossible. Nobody has ever seen anything like this before. He goes in to the room where the dead girl is. There are a bunch of people mourning her there. He tells them that she isn't dead, but asleep. Their response is "But the people laughed at him."
Man, how tough is that? Jesus is about to do something awesome, and everybody is just laughing at him for having such a stupid thought. Of course people can't come back from the dead. They're dead. To suggest that they can is ludicrous. It deserves laughter.
We all have dreams. Some of us even dare to do great things for God. Maybe even impossible things. These dreams often elicit laughter and ridicule. But if God has pushed it into our hearts, we dare not shrink away from it. I'd rather be laughed at by people so that I can hear God say "Well done." JM