Apparently, back in the day when Pirates of Penzance was being done, the Pirate King would do some stage business with one of the percussionists for laughs.
in kiss me kate (at least the revival) Fred talks to the conductor about the "cut" he added.
"Grease," the fourth revival of the season, is the worst show in the history of theater and represents an unparalleled assault on Western civilization and its values. - Michael Reidel
And who could forget the very last moment of DOTV where it was revealed that Mikey Crawford aka Krolock had been the conductor for the show the whole time!
This is a really weak example, but during the Finale of Pippin, the conductor screams, "Get your damn hands off of the piano!" and eventually the entire orchestra leaves.
Recent Broadway and Off-Broadway:: Carrie, Merrily, Ionescopade
Next On The List :: Clybourne Park, Once, Streetcar, BOM
"It was the nicest little whorehouse in all of Texas. It lay about a mile down this old dirt road and if you just happened to stumble on it, you couldn't help but notice that the barns were painted, the fences were up and you might think to yourself 'Folks who live there might just be fun to run the river with..."
Not exactly on point, but let us not forget "vocal minorities." In the written orchestrations for Company and Promises, Promises there are extensive sections for a chorus of singers to be included along with the instruments. I was in the vocal minority for Company once. You can hear the minority faintly, but clearly, in some parts of the 1970 cast album.