You couldn't hear a dump truck driving through a nitroglycerin plant.

6 seconds sound clip from the Christmas Vacation (1989) movie soundboard.

You can hear this line at 01:19:29 in the Blu-ray version of the movie.

Quote context

[...]

- Are you okay?

- I'm fine, honey.

(CHAINSAW NOISE)

- Fixed the newel-post.

- What's that sound?

- Do you hear it? It's a funny squeaky sound.

- You couldn't hear a dump truck driving through a nitroglycerin plant.

- Shh. I hear it too.

- I don't hear it anymore.

- Quiet! Shut up!

- Mom, don't move.

[...]