A singalong that’ll slay you

“Buffy the Vampire Slayer” was always a genre-busting anomaly, combining elements of horror, gothic romance, soap opera, satire, even slapstick. But “Buffy” went to show-stopping lengths in its Nov. 6, 2001, episode: “Once More With Feeling” featured the cult hit’s assortment of slayers and demons breaking into song (11 in total), all composed and written by the show’s Stephen Sondheim-worshiping creator, Joss Whedon. Heck, there’s even an overture. “It was a nightmare,” Whedon said of the process. “The happiest nightmare of my life.” Which is pretty much how many of us felt about “Buffy.” Some of the show’s fans are hosting a singalong screening of “Once More With Feeling,” plus the “Angel” episode “Smile Time,” in Pasadena on Friday. The evening honors the 10th anniversary of “Buffy” on TV this year; proceeds benefit the Elizabeth Glaser Pediatric AIDS Foundation. Should be bloody good fun.

“Once More With Feeling”/”Smile Time,” Laemmle’s One Colorado, 42 Miller Alley, Old Pasadena. Friday, 10 p.m. $15. (626) 744-1224.