In the Everyone Orchestra, conductor and founder Matt Butler shepherds willing participants both on- and off-stage to perform in an improvisational style. The rotating ensemble has accumulated members of the Grateful Dead, String Cheese Incident, the Flecktones and Maria Muldaur, as well as Tuvan throat singers, hula hoopers, fire spinners and jugglers. Together, these acts follow the lead of the conductor’s hand signs, whiteboard and various mime suggestions. Enjoy the randomness when the Everyone Orchestra performs on Friday, June 21, at the Mystic Theatre. 23 Petaluma Blvd. N., Petaluma. $23—$25. 9pm. 707.765.2121.