Jump up onto the nearest table, throw your arms in the air, bend your knees and yell "INCOMING!" at the top of your lungs.
Either that or my personal favourite...
"Ladies and gentlemen; we have had what can only be classified as an potentially deadly anal emission ejected into the nearby atmosphere. Please put on the nosepegs located conveniently underneath your seat. If you are unfortunate enough to not have a peg, please pinch your nose and pray for your life"
Most people spend so long trying to figure out what the hell you even said, they either don't notice the smell or it's gone before they can properly complain.