Loose Screws, the longest-running improv comedy troupe here, marks its 15th season with "The Loose Screws 15th Anniversary Show: Crystal Balls," at 8 p.m. Saturday at Tenney Theatre, Saint Andrew's Cathedral.

The performing ensemble includes Monica Coldwell, Squire Coldwell, R. Kevin Garcia Doyle, Sharon Garcia Doyle, Walter Eccles, Meredith Desha Enos, Matt Miller, Sean T.C. O'Malley and Jennifer Waihe'e. They are joined by alumni Stephanie Conching, Garrick Paikai and Shannon Winpenny, with additional participation by Chris Riel and Shawn Thomsen of the improv group IYF.

In the last 15 years, Loose Screws has performed in Los Angeles, Chicago, Seattle and the Big Island. The group is preparing to take its signature show, an improvised Kabuki titled "Screwbuki," to the Edinburgh Fringe Festival in August, 2010.

Tickets are $10 if you buy by Friday, $15 at the door. Call 550-8457 or go to honoluluboxoffice.com. There's an additional $1 discount, or cash back, if you bring an unusual item that the cast can use in the show.