Drag

To investigate Monsieur Coiffure, the Sixth Doctor had Nesta Trubshaw put him in drag. (AUDIO: The Vanity Box)

While in her wedding dress, Donna Noble found herself mistaken for being in drag by passersby in London. A group of men in a passing car shouted "You're fooling no one, mate" at her as she waited for a taxi to stop. (TV: The Runaway Bride)

Behind the scenes
Drag is the performance of gender for an audience, often playing on exaggerated stereotypes. In this case, Donna is being perceived as a drag queen for dressing up this way outside the expected norms.

Though drag has historical roots in trans culture, and continues to be an important tradition within the community, the implication here is that they think Donna is a cisgender man "dressing up" as a woman. That they would refuse her access to transportation is rooted in transphobia.