Gamers laugh at things in different ways.
I’ve noticed that gamers laugh at odd occasions sometimes. It’s a laughter that could most appropriately be called “lulz”. It sounds like ordinary laughter, but it’s very different. Let me explain by example:
You and someone else are running somewhere. Someone else falls over, and you start laughing at them. That’s ordinary laughter. Then, from laughing, you fall over, and then you both start laughing. That’s lulz.
You’re laughing at the situation, the chaos of it, the randomness. It doesn’t involve belittling you or the other person. It’s not about personal vendettas or racial stereotyping. It’s just something crazy. It’s you stabbing someone and someone else stabbing you while you weren’t looking and the grenade you dropped killing him. That’s why “lulz” is such an appropriate word: There’s no winner or loser in the laughter (although sometimes there is a winner, but it’s more of a Steven Bradbury moment). It can best be described by internet style FML posts or the motives behind Lulzsec.
But here’s the thing: Most normal humans don’t understand this laugh. They’ll misinterpret it and think you’re making fun of someone. They might say “Dude why are you laughing you fell over too”; "Err yeah that’s why I’m laughing..." Certainly something a gamer needs to think about.