Robitussin? Nah. Heroin
Too bad we weren't around in the 19th and early 20th centuries! That's when they forgot about Robitussin and used heroin instead to calm coughs. http://books.google.com/books?id=HFO_bUEt3IsC&pg=PA147&lpg=PA147&dq=calming+coughs+heroin&source=bl&ots=d86K_aqxq4&sig=cb6PSDQxR-oGxL6XzMm5lCo-Gts&hl=en&sa=X&ei=kJ3UUJDJJ8nE0AGJ74CIBg&ved=0CEgQ6AEwAw#v=onepage&q=calming%20coughs%20heroin&f=false