i laugh as a defense mechanism for any number of things including the things you said sometimes. I also smile very heavily as a defense mechanism (far more often than laughing) and its sometimes problematic as it can definitely cause confusion in the wrong situation
I did this as a child which got me beat up a lot. Nowadays I can mostly suppress it, but sometimes a smirk sneaks out. I'm terrified I'll end up a social pariah or even convicted of some heinous crime because I smirk at the wrong moment (ie showing "duping delight").
I'm not entirely sure why I do this but I think it has to do with trying to be sympathetic and lighten the mood when presenting bad situations to another person. I think my mind decides to try and defuse the situation and the only way it knows how and that's smiling, even when it's entirely inappropriate.
Remember that guy who got a stroke and as result, he's unable to feel sad.
As proof, they attached a picture of him smiling in a funeral, guess he got the fun part there.
As proof, they attached a picture of him smiling in a funeral, guess he got the fun part there.