Flatulence consists of intestinal gas expelled through the anus. While flatulence is a common part of daily life, sudden changes can be important disease indicators for physicians. In this combined experimental and theoretical study, we rationalize the duration and acoustic frequency of flatulence among mammals, from rats to elephants. We perform high-speed videography and acoustic recordings of guinea pigs, humans, and whoopee cushions. The acoustic frequency is generated by the vibration of the skin of the anus, similar to the buzzing of lips in a trumpet’s mouthpiece. Thus, larger animals generate lower acoustic frequencies due to the lower resonant frequencies of the thicker and larger anal skin.