I might have started laughing if the subject weren't so serious.

Then she started laughing at the top of her voice.

He looked at her eyes for a moment then started laughing.

I started laughing for the first time in a long while.

The two men looked at each other and started laughing.

Every few minutes one of them would start laughing again and set off the other two.

And every one of them made me want to start laughing.

Then I fell back on the bed and started laughing.

We start laughing and it seems like we're never going to stop.

I started laughing because it made me feel so good.