If I ever smile or laugh at my stutter it's in response to someone doing so first. I think I do it to make them feel at ease, removes tension from the room, but it makes me feel embarrassed and ashamed because I failed at being fluent and the cat is out of the bag, so to speak. I know this isn't "healthy" because it shows I haven't fully accepted that I'm not naturally fluent. I personally don't like the idea of laughing about it. But hey that's just me.