I've never understood exactly why Firesign Theatre's media-savvy, wickedly satirical, pun-besotted comedy style--as exemplified on such brilliant concept albums as How Can You Be In Two Places at Once When You're Not Anywhere at All, I Think We're All Bozos on This Bus, and my personal favorite, Dear Friends--all but died out in the late 70s while the considerably tamer and less demanding sketch-based comedy of Saturday Night Live and Second City continued to thrive. Certainly Firesign's strong association with the marijuana-based counterculture that was already becoming passe didn't help. But I suspect the sophistication and sheer complexity of their surreal humor also scared away potential fans. Their albums--really extended one-act radio plays--were so packed with oblique references to beat literature, pop culture, science fiction, old movies, the history of radio, and past Firesign albums that only truly alert listeners could get every joke. Now, after a hiatus of 12 years, during which the comedy troupe's four members pursued other projects--Peter Bergman pushed Klondike Bars; Phil Proctor supplied voices for the Saturday morning's Smurfs; David Ossman produced a 1988 public-radio re-creation of Orson Welles's1938 War of the Worlds--Firesign Theatre is together again, reportedly working on a new album and a cable-TV movie and touring the country with a 25th-anniversary "best of" show, featuring updated versions of such Firesign favorites as Beat the Reaper and the imitated but never equalled Further Adventures of Danger. I haven't seen the show, but I'm encouraged by the possibility that after the Reagan-Bush years the world is again ready for Firesign's subversive wit. Arie Crown Theatre, McCormick Place, 2300 S.Lake Shore, 559-1212. Saturday, October 30, 8 PM. $17.50-$35.