Manner? What manners?

A few Saturday's ago we had a NEW babysitter. As we were in the living room, I was telling her a few things when Justin burped. Of course since he is so little and doesn't know better, I didn't think anything of it. The older two boys thought it was funny so Darren burped on command. They boys were laughing a little harder at this point. Before I can even open my mouth to scold them, Nathan farts. They are falling down laughing at this point. I was laughing a little bit though I tried to hide it and said, "Boys we have company. You don't fart and burp in front of company!" (I guess by saying that I said it was acceptable when it was just family?) Luckily the babysitter was holding back a laugh too.