Something Funny Going on Here

The last two nights around 8:30/9:00 JP just starts laughing that deep belly laugh that he has in his sleep. It is quite funny and I have no idea what he is laughing about. The first night he got out of bed and opened his door. At first I thought he was crying, but then when I got to him, he was just standing in his doorway laughing uncontrollably. I gently talked to him, walked him back to his bed and said good night. He continued to laugh for about 5 minutes. And then last night he had a little coughing fit and then started laughing again. Pratt jumped up thinking something was wrong, but I kept telling him that JP was just laughing. He went in and asked JP what was so funny and JP just shrugged his shoulders and laid back down. At breakfast this morning we asked him what he was laughing about and he looked at us like we were on drugs. I really wish I knew what was so funny so that we could share in the joke:)