Haha I think everyone who has had any signifigant amount of sex has farked a couple times while doing it. Once when I was having sex for the first time with a particular girl I let a really nasty one out, and she had her door open to her bedroom and her small dog had wandered in. It smelled really bad so I said, "Ahhhhg.... I think your dog just farted..." she yelled at the dog got up, put him out and closed the door, and we continued.
These days when I do it, I ask my wife, "Baby did you just fart?" Even if she didn't she just goes, "sorry.... don't stop..."