Are you by any chance Polish, tall and work in computers, especially programming? I had a Polish friend who always laugh when he's in trouble, especially when customers is yelling at him and he just laughs. He still laughs even when he's not in trouble but there's usually nothing funny to laugh about.

Our boss had a huge stack of complaints from customers about his laughter because they thought he was mocking them.

I asked him about it and he said he don't know why he would laugh during these moments and it's not what he had intended on doing but it just basically came out on its own and he had zero control over it.