What with you do in this situation?

Well, if it wasn't obvious where the noise came from, I'd look accusingly at the person next to me. I've done this before, and it's very effective. If I have to hold my hand up, I'd play the sympathy card and say, 'Please excuse me, but I have a serious, incurable bowel problem. Thankfully it's not terminal, but it is often embarrassing, as I have no control over it.' This also works well, although it's completely untrue. As far as I'm concerned, all's fair in love and flatulence.

I just do a tiny giggle, raise my hand to my mouth as if in shock that it even happened and say "Oh pardon me." Works every time. After all everyone knows it's something we must do at one time or another, and sometimes no matter how hard we try we can't save it for a more appropriate moment. Other times the darn things just sneak up on us LOL!

I would probably laugh and say- 'I farted!' I usually do. Everyone will forget about it soon, so why the heck no? xD