Eat gas-inducing food and fart really loud. Laugh every time. The laughter will become contagious and disruptive to the program. First the kids will giggle because they can't resist a good poo joke. Then it will be the teenagers, then everyone will just start laughing.
If you can't produce a fart at least 4x per hour naturally, I'd suggest getting some apparatus from a practical joke store to simulate them.
Do this for a few hours, then start faking cramps. Squirm around in your seat, holding your belly and groaning. Get louder and louder.
This should all climax by you jumping up and running out of there really fast, groaning, "oh noooooooo". Keep running past the bathroom and straight to your car.
This should be 100% effective.