Cowboy, it's Sergeant Murphy.
3 seconds sound clip from the Jaws (1975) movie soundboard.
You can hear this line at 01:32:10 in the Blu-ray version of the movie.
Quote context
[...]
- Okay, then save your ammo. Nobody fire till I tell you.
- No, no. Cease fire. Cease fire.
- Cowboy, it's Sergeant Murphy.
- This is Murphy. What is your present position? Over.
- Murph, we're receiving enemy sniper fire.
[...]