The off-Broadway sensation Blue Man Group began selling out the Charles Playhouse's Stage I as soon as it arrived in 1995. The trio of cobalt-colored entertainers backed by a rock band uses music, percussion, food, and audience members in its performance. It's not recommended for children under 8, but older kids will love it. Shows are usually at 8pm Tuesday through Thursday; 7 and 10pm Friday; 4, 7, and 10pm Saturday; and 2 and 5pm Sunday (with extra days and performances during the holidays and school vacations). Tickets are available at the box office and through Ticketmaster (tel. 800/982-2787).

Shear Madness, on Stage II (downstairs), is the longest-running nonmusical play in theater history. Since January 1980, the zany "comic murder mystery" has turned the stage into a unisex hairdressing salon -- and crime scene. The show's never the same twice; one of the original audience-participation productions, the play changes as spectator-investigators question suspects, reconstruct events, and then name the murderer. Performances are Tuesday through Friday at 8pm, Saturday at 6 and 9pm, and Sunday at 3 and 7pm.