private void button2_Click(object sender, EventArgs e) { ScaryScary fingersTheClown = new ScaryScary("big shoes", 14); FunnyFunny someFunnyClown = fingersTheClown; if (someFunnyClown is IScaryClown) { IScaryClown someOtherScaryClown = someFunnyClown as ScaryScary; someOtherScaryClown.Honk(); } }