Why the countdown?

4 seconds sound clip from the The Green Berets (1968) movie soundboard.

You can hear this line at 00:16:55 in the Blu-ray version of the movie.

Quote context

[...]

- Pack in 10 minutes? Takes me longer than that to get my heart started.

- What are you doing?

- I'm packing!

- You pack what Uncle Sam issued and that's all.

- You got 9 minutes.

- Why the countdown?

- You got 8.

- Eight?

- Where are we going?

- You'll get the word.

[...]