SONiVOX's Anatomy is the only program I can think of that has sampled flatulence with editable parameters. Now you can pan your gas left and right and add effects. The possibilities are endless. Put on a nice slapback delay and pan the feedback left and right.

Why didn't anyone think of this sooner?

Oh yeah, it does contain more than just farts. In fact, it contains pretty much every noise the human body can make. In unrelated news, look for a new Bjork album sometime soon.