This is a good weekend for people who are adventurous, as far as theater-going is concerned.

Inquire: JFK Memorial Bomb Shelter. This show has been described as "a Bicentennial play for peace." When asked to elaborate, the man at the box office (he was actually only an electrician everyone else was out getting pizza, he said) would only babble, "I can't describe it, like, you just gotta see it, you know?" Tonight and Saturday at 8 at the Boston Center for the Arts, 551 Tremont St.

The Madhouse Company of London. This one is billed as "a Wild Stunt Show," but rumor has it that it is actually a revue compiled from old vaudeville acts, and Off-Broadway. All know for sure, though, is that one night last week they were giving out prizes to members of the audience who showed up in clothes that displayed really bad taste. At the Charles Playhouse in Boston tonight and tomorrow at 7 and 9, Sunday at 7:30.

First Amendment. For the truly adventurous, this newly formed acting company is offering an unspecified "Bicentennial and other theatrical plays." If that doesn't satisfy your curiosity you can try calling 267-7196, but don't necessarily expect an answer. One thing, though whatever it is, It's free. At the First University Church in Boston tonight at 7:30.