"Nervous laughter" refers to a type of laughter that happens when someone is feeling anxious, uncomfortable, or stressed. They may laugh to try and hide their true feelings or to release tension. Full definition
Every now and again he would comment «well at least you're still laughing», simply drawing attention to the fact I was filling dinner with nervous laughter. (30datesblog.com)
I kept hearing nervous laughter while visiting the show. (magazine.art21.org)
The real revelation, though, is Priven, who's so wholly believable he milks any possibility of nervous laughter out of his scenes. (edition.cnn.com)