Ok it happens, people belch. Ideally this is not intentional, but intentional or not, it does occur. Hopefully, the offendor at least has he etiquette knowledge and decency to appoloize and excuse himself or *gasp* herself. When this doesn’t happen you are in every right, nay, it is your duty to apologize for the offensive burp.
Gentle indicator: “Oh, excuse you.”
Truly foul: “That was quite rude. Next time please keep your burp to yourself. Thank you.”
Feel free to stomp away.