The Doctor: Mona Lisa, that dreadful woman with no eyebrows who wouldn’t sit still.
Doctor: I’ve never cared much for the word “impregnable.” Sounds a bit too much like “unsinkable.”
Lethbridge: What’s wrong with unsinkable?
Doctor: Nothing! As the iceberg said to the Titanic…
Lethbridge: What?
Doctor: Glug, Glug, Glug.
The Doctor: You’re a classic example of the inverse ratio between the size of the mouth and the size of the brain.