Some guy in one of my lecture's wouldn't stop, and I was right beside him. It sounded like a low rumbling that slowly reached a crescendo but were kinda muted so it still didn't sound like someone was passing gas. I looked over at my friend that was on the other side of him, and they had the most bewildered look on their face as another mid-crescendo occurred. What made it funnier was that he was trying to move around acting like his foot scraping the floor or his increased typing speed was making the sounds
The guy said something about it himself during the 1 hour mark break, but no one really heard him, and they started back up ass soon as the lecture started up again.