To clog up someone's bathtub with toilet paper and take a shit in the tub then leave the hot shower running over it to humidify and make the fecal matter airborne
Someone shit steamed the frat house at St. Mary's College of Maryland
On the farm, when a cow is taking a shit and, in the process, Coughs causing an explosion of shit to hurl from its ass at light speed. Most often a witness to this even will tend to use the phrase to describe the speed of an object or vehicle.