Lallycooler is a two-day, large-scale summer music festival in Sioux Falls, S.D. Lallycooler brings big artists and music lovers of all kinds together for an unforgettable experience in the scenic setting of Great Bear Ski Valley. Lallycooler means “a real success,” and it will be just that — from the music to the food, unique experiences and more. The 2025 festival will be the first, and you don’t want to miss it.