- It's quite harmless until it's detonated.
- Thanks for telling me.

5 seconds sound clip from the The Bridge on the River Kwai movie soundboard.

You can hear this line at 01:21:00.142 in the Blu-ray version of the movie.

Quote context

[...]

- Well, come along, then. Colonel Green is looking forward to meeting you.

- Oh?

- Fascinating place, isn't it?

- Utterly charming. I didn't realise it was a commando school.

- We're trying to discourage that word. It has such a melodramatic air about it.

- What do you do here, major?

- Oh, sabotage, demolition, that line of country.

- We're using P.E., plastic explosives. It's wonderful stuff. That last little pop was made with a lump half the size of this. It's twice as powerful as gelignite and only half the weight. Here.

- It's quite harmless until it's detonated.

- Thanks for telling me.

- It's completely waterproof and actually plastic. See? You can do what you like with it.

- This is my place. Go ahead.

- Oh, I'm dying for a cup of tea. Would you care for one?

- No, thanks.

- A drink?

- No, thank you.

- Pot of tea for one, please, Peter.

- Very good, sir.

[...]