If I am thinking of something funny I usually chuckle for awhile if I am alone, and just smile a lot if I am with other people, but sometimes I laugh until I can't breathe. Used to happen a lot in school when the whole class would act up and our teacher would yell and everyone would get quiet because she's angry, I would always be the first person to start laughing again at the situation and make everyone else start laughing again.
It usually happens in inappropriate places for me. Like in a class or a library. And... well, I guess, once at a funeral too. I don't think that anyone noticed though, I hope at least.
Another place is a cafe, when I should be telling what I'd like to have. For some reason it always seems incredibly funny to me.
I was laughing almost hysterically at a funeral once, but it was a real quiet sort of laugh, you could just see my body sort of shaking, so someone could have passed it off as crying. i wish i could remember what was so funny.
I remember back in the Fall in one of my classes, I came in and there were these 2 girls I was sitting next to. One of them, omg, I could smell her shampoo so intensely from where I was sitting. I told her about it. We just laughed, and then during class, I started giggling. After 5 minutes, I was bursting into laughter randomly. She kept laughing everytime I laughed, and I was trying so hard to control myself. We were at the front of the class, too. The teacher asked me to leave the class if I didn't get control. The class thought I was weird, too. No one but me and the girl knew what was so funny.