It happens to me occasionally. Usually when I'm drinking and smoking at the same time. The funniest was I was off from work one day, so I had blazed and had a few drinks. I got a call from my office and had to go to unlock a cabinet. So I just threw on some sandles and went in. So now I'm talking to a few of my coworkers and all of a sudden...BURP. One coworker says that it sounded 'meaty', a coworker that knew I smoked said, "No, I think it's more of a vegetarian burp".