B: Believe me, Doctor, the place is impregnable.
D: Never cared much for the word ‘impregnable’. Sounds a bit too much like ‘unsinkable’.
C: What’s wrong with ‘unsinkable’?
D: Nothing. As the iceberg said to the Titanic.
C: What?
D: [IMITATES SINKING] Gulp, gulp, gulp, gulp, gulp, gulp.