Maine Roller Derby’s Calamity Janes will host the Petticoat Punishers of Worcester, Mass., at 6 p.m. Saturday at the Portland Expo. The doors will open at 5. Advance tickets are $10 each or $35 for four. Admission is $13 at the door, $5 for ages 6 to 12, and free for those 5 and under. Tickets are available online at www.mainerollerderby.com or at Bull Moose Music.