Farts are inherently funny. They are rude and offensive and can be controlled. And they sound funny. And they stink.
What's not to love?
A few years ago my family and I were in Vegas for a week. My son had been scarfing down chili cheese fries all week. We took a rental car to Utah for a day. When we turned that rental in, I'll bet National took it to a bad part of Vegas and left it running with the keys in the ignition. God, was it BAD!
Better to die on your feet than live on your knees.