Yes. Especially in bad times. I remember once me and my sister got in a car accident when some old drunk guy at the school pulled out while we were going through the parking lot (Yes, drunk at a school). He had the entire stretch of parking lot to see us coming through, pulls out real fast and hits us, Then when the accident is over he asks "Whoah, where'd you come from?" My sister is just furious and she's yelling and I'm sitting there laughing! I have that weird nervous laughter people hate. I'm belly laughing and she's screaming and this drunk guy is just plane clueless.
What's worse is it wasn't even our tuck, my sister was borrowing it. So when she was too shy or too emotional to explain what happened I had to tell him, I couldn't get through the story without laughing which just seems careless and cruel.
Oh, If only there'd been a camera...
(This is just one example of laughing in the worst of times. Like once, during a science experiment with two lab partners in 6th grade we were cleaning up and a roll of paper towel went over a lit candle and it just started a fire, 2/3 of us in the group couldn't start laughing after that. It's just a natural reaction some people have and everyone else hates)