MissAlgernon wrote:
Polite people never burp, never fart, never need to go to the bathroom, and never produce disgusting waste in general, because they're immaterial angels coming from Heaven. If you do, it's a sign you're an inferior being who forgot to evolve. And that isn't eco-friendly either, you're contributing to global warming.

/sarcasm off
More seriously, yes, burping is considered rude in the western world. It isn't universal though. In Maghreb, burping after eating means that the meal was good.
Ah yes, but in the case of 5th grade boys, we were required to burp...uh, belch...and when doing so, we obtained much extra credit for being able to voice recognizable words. For instance, a friend of mine always enjoyed riffing off the phrase "Ralph Nader" while expelling billows of gas from his stomach.
Now, I'm not saying we aren't polite, but for guys, there's always a little 5th grade boy inside...