Everyone burps
I don't. Well, not really, I only make low, distorted growling noises. They are more drawn out than a burp would be and whenever I start doing it, I keep doing it for quite some time. I can't really control it, the only way to stop it is to stop breathing.
It's not very loud, but you do notice it when it's quiet or I happen to have my mouth open at the time, like when I'm talking. It really confuses most people.