Once when I off work with a flu/virus type thing I let one go as i was walking to the kitchen. Problem was it wasn't just air that came out. It was quite an upsetting moment.
I was in one of these cheap superstore places like Matalan with my ex a few years back - we got to the food section where they had the bargain beef, steaks, chicken etc and he let off the most disgustingly smelly fart you have ever smelt - when people started smelling it, he annouced that the meat must be off and that no one should buy it.....The asile cleared in seconds