A group of terrorists take over the theater. In this case it was the Ambassador No idea what happened at the end but it was not a Broadway classic. The terrorists surrendered after 7 performances. I saw it and it was a real hoot. Some people actually believed it was really happening.
I remember seeing it and being really annoyed with myself that I got seats so close to the stage on the aisle (must have been a big discount - I would not have paid much for that premise). As lame as I thought it was, I was really uncomfortable at times. I remember a person near me being pulled up on stage...clearly, he was an actor, but it was still disconcerting.
Thinking about it, I think the basic premise was very clever...the script was just not good enough. I also don't remember how it ended, although I do seem to recall the lead getting shot.
In the spirit of adding to the list, the dumbest play lay that I can ever recall was The Leaf People, at the Booth. It was presented by the Public Theatre, and must have had 20+ people in the cast. The entire thing was in some made up language, with translators in two pods elevated on the stage relaying what they were saying. I remember thinking that the Public Theatre must have had too much money (must have been after A Chorus Line opened), and decided to throw it away. It was torture. I remember the only reason we stayed was to see if there was any point to it...we could not find one.
For musicals, I think the all-time bomb that I saw was Dr. Jazz. Had Bobby Van right after No! No! Nanette. Took place in a brothel in New Orleans. Remember very little because we left after 30 minutes, right after two obese whores took to the stage in see through outfits...wanted to barf. It got crucified by the critics And ran for 4 performances, although Lola Falana got nominated for a Tony in a really bad year...I don't think there were 5 actresses in a musical and rules were rules.