Histrionics are the show itself — the tears, the shouting, the how-could-you performance meant to pull sympathy and attention. People almost always say it in the plural, and they almost always mean it as a complaint: stop the histrionics means stop acting as if this is a play. It can sound a little old; younger people might just say drama. Though actually, it is not quite the same as a child's tantrum. It points at grown-up theatre: feelings worn on the outside so other people have to watch.