Typhoid Mary. Public domain image.
My mother used the term Typhoid Mary to refer to negative behavior by someone who seemed oblivious to its effects. Why that name? Because that’s actually what the real Typhoid Mary (Mary Mallon) was about. She was a carrier of typhoid fever but not infected herself, and she didn’t understand why she should modify her behavior.
Read more about her in this article by About.com’s Jen Rosenberg: Typhoid Mary