I know this may be a little irreverent, but I think Heber would laugh.
When my oldest son was about 6, he came home and told us of a friend of his who could make fart sounds with his hand and armpit. I have never been able to do it, but Merrily told him that her brother could. In fact, he could make fart sounds with almost any part of his body! So, Paul & Seth waited excitedly for their Uncle Heber to visit. When we pick up Heber and Olya from the airport, Paul immediately asked Heber to show him how, even before he was in the car. We tried to tell Paul to wait, that it was inappropriate, but Heber obliged and "PFFFT, PFFFT". Giggles ensued the whole ride back to our house. Then he showed them how to do it them for selves. Paul got it right away. After more persistent begging on Paul and Seth's part, Heber showed how he could make fart sounds with just his hands, then his hand on his ear, and finally, laying down with his shirt off, with his back on the floor. To this day, that is Paul and Seth's favorite thing about their uncle Heber.