There are times where I will start laughing and can't stop. I use to embarrass my kids when we were in public. It would be over the stupidest things. My husband has encountered this also. We've been together for over 2 years. He doesn't even know what to make of it. Sometimes I will be thinking of things that happened and I will just start laughing. All he can say is ALL RIGHT. BREATHE. I can't explain why it happens to him. I remember year and years back when I got really depressed I sometimes would start laughing and that's when I noticed I was even doing it. I guess I'm really strange but it doesn't bother me.