Three times. I got it.
4 seconds sound clip from the Platoon movie soundboard.
You can hear this line at 00:17:11 in the Blu-ray version of the movie.
Quote context
[...]
- What?
- You sure you know how to work the claymores, dude?
- Flick the safety off and bang on that sucker three times.
- And don't catch any Zs on me, buddy, or I'll sling your sorry ass. You hear me?
- Maybe I finally found it, way down here in the mud.
- Maybe I can see something I don't yet see or learn something I don't yet know.
- I miss you. I miss you very much.
[...]