You'll probably find Ed outside smoking a coffin nail. 2. slang An alcoholic beverage. Here's another coffee nail for you—you'll be drunk before you know it. See also: coffin, …29/03/2018 · Hard as a coffin nail. 4.91/5 (22) Very hard. Post navigation. Previous.The interpretation link is more than likely reinforced by people having heard cigarettes dubbed “coffin nails” or, more mainly, harmful things being called “another nail in (his, your, my) coffin”. And that simply now made me wonder if some people can be utilizing the eggcorn “coughin’ (or coughing) nail”.