Laughed at (whoopee)

I was at a professional occupation the other day, because I had an appointment. Already whenever you go to this it's probably one that you dread or are already embarrassed. Me being me I was already nervous thinking it was going to go worse than it was. The receptionists weren't very welcoming. At first when the one of the ladies started laughing, I just assumed it was nerves, and ignored it, but when I made eye contact with them and they started belly laughing that's when I knew it was at my expense. All I did was ask "do I need to pay?" and the receptionists made us wait because they wouldn't stop laughing. It was so embarrassing. Do you know what would've made them laugh? All I was doing was avoiding eye-contact because I didn't want to be weird and just stare at them.