Navvy

A navvy was a name Charles Dickens derisively called the Ninth Doctor upon their first encounter on Christmas Eve, 1869. Dickens made the comparison on the basis of the Doctor's attire. (DW: The Unquiet Dead)

In real life, a navvy was a manual laborer who was typically engaged in the construction of civil engineering projects. The term was especially in use in 18th century Britain, and chiefly employed with respect to the "navigational engineers" who built Britain's navigational channels, or canals. Thus, Dickens' employment of the term was a class-based insult.