A coffin is chasing a man down the street. The man runs into his house, closes his door and locks it, but the coffin keeps breaks through, he hides in the kitchen, but the coffin finds him and keeps chasing after. The man runs upstairs into his room, locks the door and barricades it, it isn’t safe there either, the coffin busts through. He runs into his bathroom, cornered, frantically searching for a weapon, but all he can find is a bottle of Robitussin in his medicine cabinet, he splashes it on the coffin and the coffin stops.
For those who don’t get it (I didn’t either at first), Robitussin is a cough medicine.