They think they're very clever.
2 seconds sound clip from the The Invisible Man (1933) movie soundboard.
You can hear this line at 01:00:43.174 in the Blu-ray version of the movie.
Quote context
[...]
- Why not paint the top of the wall?
- They think they're very clever.
- All right, take him straight inside.
- Twenty minutes to 10:00. Keep your eyes open now, boys.
- Here, quick, sir. I heard footsteps outside. Soft footsteps, like naked feet. Listen.
- In the mountains, 100 miles away. Drive away quickly.
- Well... It's ten minutes to 10:00. He's bound to do something any minute.
[...]