No, this isn't a microorganism that cracks bad jokes. It's a pathogen whose toxic strains cause diphtheria, a potentially deadly disease in which toxins coat the infected person's throat and make it difficult to breathe. Diphtheria starts as a cold, before graduating to a fever and chills, and even heart attack [sources: CDC, Murphy].
Fortunately, vaccinations are widely available in developing countries. In the U.S., the disease is largely nonexistent. That means that the corynebacterium found on cell phone swabs taken by University of Oregon researchers in 2014 probably weren't of the toxic variety [sources: CDC, Murphy, Munoz].