I did it one time. My stomach felt so full and bubbly after, that I had to stand up straight and rub it. I was going to see how much I could hold in burps, but all I wanted to do was to burp because the pressure became painful and I thought I was going to be sick.
Then my chest became full of gas and little burps kept coming out for hours after that, they were audible but not as big as I thought they would be. I was too bloated and gassy to do big burps, I just let them come out naturally to avoid being sick.
The burps were very banana-ry, and were quite gross sounding, like “broop”.
In bed that night my stomach was making all sorts of loud gurgling noises and the burps were still coming, although I had to keep sitting up to burp as they wouldn’t come up when I was laying down. But they started getting bigger and less gross by then.
I don’t think I’ll ever do that challenge again. I felt like I was going to explode. Just couldn’t stop belching.