Turning a criminal archetype into a cough-medicine hero is a little weird. It also makes surprisingly good psychological sense. Robitussin has introduced Robby Tussin, a deadpan “cough hitman” who appears when a cough becomes unacceptable, reaches ominously inside his trench coat and pulls out… cough syrup. In one ad, a coughing man in a restroom tells him, “Do it quick.” That’s dark territory for a 77-year-old medicine brand. It’s also pretty creative. Haleon says this is Robitussin’s...