Paul Dirac had a very quiet and taciturn nature. His colleages in Cambridge even defined an unit, the "dirac", which represents the minimun amount of words that can be spoken on a conversation. Thoroughly, a word per hour. If you want to know more about Dirac, hey, you just have to search for him in Wikipedia.
This joke came to me after a conversation with my dear friend Paloma (a.k.a Palomeision) in which we both were particularly... monosyllabic. Then, after a long silence, she said to me 'feeling Dirac today?'. I laughed a lot.