I was at a Super Bowl Party this evening and had bad gas. I held in the farts best I could. Do they still leak out and smell if I don't fart?

If I hold them in does the gas still leak out or not until I fart which I did after the party? Also if I am sitting on a couch and my bottom on the couch does the fart still smell? The little bit I did was with me sitting on a couch. Their were guests and so I was embarrassed. Jim: Not Trolling, a serious question.