Well, with Rudd it’s “coming from the balcony”. With Bertolt Brecht, it’s “coming from the basement”. You need to take a roll of toilet paper to get through a Brecht play. And yes, Equus made Roy Rogers’s horse Trigger show his appreciation of the play by dropping a load of horse hockey in the lobby.
So,he decides he can take it, and the opera starts. Pretty soon, he's realized he's made a grievous error in judgment...and his eye teeth are floating. He struggles and tries, but finally the pain is too great. In the middle of the performance, he gets up and cries out in a loud voice “Stand clear below, for I must make water! And oh...the pleasure of it!” He then undoes his trousers, whips out his equipment, and proceeds to let fly over the side and onto the floor below. Needless to say, he made quite a splash...and was also ejected from the theater.
I do not have a source for the story, but I remember reading it many years ago and laughing myself silly when I did