Proper etiquette when dining at someone else's house?

My roommate has a friend from Sierra Leone and he seems like a well mannered gentleman. However, and this is the absolute truth what I am about to tell he, when he around others and lets one, he will actually not hold back and just let it go and then he says pardon me and keeps on talking or doing whatever he was doing like nothing happened. I mean, the first time he did it, we busted out laughing. I mean they don't stink bad or anything, but there is no way I could do that and then excuse myself. I would be way too embared. The question I have is this. Is this normal in Africa? I mean do they just let it out and not hold it in. I know in the USA, we just pinch it back until we can get somewhere to discreetly let it go.