Um. I'm trying to think of ways to state this delicately...
The ultimate goal of taking a yoga class (and pilates for that matter) is that you have to be sufficiently relaxed to get your body to move into certain contotrtions that your body would normally find offensive.
Occasionally, someone gets so relaxed that they...um...let a big dry one rip.
The first time I was in that situation it was in a group yoga class at the student rec center in college and it was a packed class. Some guy just got so relaxed that he subwoofered one right through his spandex shorts. The teacher said, very deadpan, "Thaaaat's right, relaxation is the ultimate goal of yoga." I had to clench my jaws together to not giggle.
I'm quite sure instructors learn to expect these, um...outbursts and stop noticing them. Well, it happened around me yesterday for the second time...and it was one of those fleshy people who look like they stink when the work out.
We were were doing seal or some pose like that and...*sigh*
I'm an adult, so I kept myself composed, but in my head, y'all, I was rolling on the floor laughing.