Black satin cape with red lining

I do NOT recall ever watching a live musical performance. If I did, those did not stand out in my mind. When I was in elementary school, I recall watching the actors out among the children. The teacher said there's the bad guy, who was dressed all in black --- cape and all. All the children went "boo". Of course, I saw some mistiness in the eyes of the actor. So I didn't know what else to think back then except wondered why people don't like the "bad guy"