MIDLAND, Tex. — It was early in the show when members of the audience grabbed fistfuls of popcorn and threw them toward the stage. They chucked more popcorn as the evening went on, onto the floor of the crowded downtown theater, up in the air and at the people around me. The behavior was not only expected, but encouraged.

On Friday and Saturday nights in the summer, Midland sets its West Texas manners aside.

This is when thousands of people pack the Yucca Theater each summer for a raunchy, corny vaudeville-and-dancing melodrama during which members of the audience boo, cheer and toss popcorn at the stage and at one another. It is a 67-year-old Midland tradition called Summer Mummers, and it has quietly become one of the rowdiest and messiest experiences in American theater. Buttery popcorn is sold, thrown and occasionally eaten in bulk — in grocery store paper bags cut in half. The organizers claim Summer Mummers sells more popcorn in its annual three-month run than any local movie theater sells in an entire year. This summer, popcorn sales were expected to hit $110,000.