The popular Off-Broadway “20at20″ program returns this September. From September 8th through the 20th, people can get tickets to numerous Off-Broadway musicals and plays for just $20. The catch is that these $20 tickets aren’t sold until 20 minutes before showtime, and they are subject to availability (so if the show is already sold out for that night, you’re out of luck). Off-Broadway shows seldom sell out, though, so it’s worth a trip to the box office of whichever Off-Bway play or musical you’re most interested in 20 minutes prior to curtain to see what is available. You should also keep an alternate show in mind so that you can run over to that box office if your first choice isn’t available. The Off-Broadway shows participating in 20at20 this year include Altar Boyz, Awesome 80s Prom, Blind Lemon Blues, Fuerzabruta, In the Daylight, Magic and Zone, Puppetry of the Penis, Sessions, Stomp, The Columbine Project, The Fantasticks, The Gazillion Bubble Show, and The Toxic Avenger.