Heh, this is definitely an interesting topic. :xd:
Yes, I would fart in class quite a few times when I was in middle school and high school. In college, I'm able to hold it in since the classes are much shorter. XD
If I knew it would smell, I would hold it in, but if it was to be silent and innocent, I'd let it out gently and pray that nobody smelled it. Sometimes it worked, but a lot of the time, it didn't.