MUSIC What: More than 100 Denver musicians, comedians, and DJs flood South Broadway's music venues for the Denver Post's 8th Annual Underground Music Showcase. Why: Catch this year's Top of the Town pick for local band, Hello Kavita, as well as bluegrass band Zebra Junction and singer-songwriter Joshua Novak. Bonus: An outdoor stage and a Tetris video-game competition ramp up the showcase. Details: Fri 5:45 p.m.-2 a.m.; Sat 1 p.m.-2 a.m. Multiple venues on South Broadway. $20. For more information, visit www.dpums.com. COMEDY What: In what promises to be a marathon of improv comedy, Bovine Metropolis Theater hosts 24 hours of spontaneous acting. Why: Denver's longstanding SansScript players run the show, but every hour a new group will step onstage to perform with them. Bonus: Proceeds benefit Family Tree, a nonprofit dedicated to helping Denver families overcome child abuse, domestic violence, and homelessness. Details: Fri-Sat 6 p.m.-6 p.m. Bovine Metropolis Theater, 1527 Champa St. $8. For more information, call 303-758-4722 or visit www.bovinemetropolis.com.