 Buffy the Vampire Slayer developed an enthusiastic fan following while it aired . Following its series finale , fans continued their appreciation in theater showings of " Once More , with Feeling " where attendees are encouraged to dress like the show 's characters , sing along to the musical numbers , and otherwise interact in the style of The Rocky Horror Picture Show . Clinton McClung , a New York @-@ based film programmer , got the idea for a sing @-@ along from audience @-@ participation showings of The Sound of Music in 2003 . The next year , he began putting on sing @-@ alongs to " Once More , with Feeling " in Boston 's Coolidge Corner Theater , which became so popular that it went on the road . Audience members received props to use during key scenes , as well as directions ( for example , to yell " Shut up , Dawn ! " at Buffy 's younger sister ) , and a live cast performed the episode alongside the screen . 
