Most of the time when I laugh these days it is a pretend laugh to lessen the seriousness of something I just said, when it appears the other person thinks it's worse than I did. On some rare instances, I'll get tickled by the slightest thing and laugh till I cry and it's not really about how funny whatever happened was but more so it was a moment I was capable of laughing I think. Oddly enough, those tears of laughter have become tears of sadness at times. It is my belief that there are little windows of time that open up where we can feel things we aren't used to reacting to, like something funny for example. Those little windows can let anything through, which I think is why sometimes laughter may be suppressed, as maybe we remember some other time when the laughter turned to other negative emotions before the window could be closed again. Just my rambling 2 cents.