it was either a movie or tv but I remember a group of people or maybe one person whistling before doing something to someone, I remember thinking it reminded me of the hunger games whistle and maybe they whistled before killing someone or something but it was something they always did. it may have been a horror I don’t know
Was it Kill Bill 1?
https://m.youtube.com/watch?v=-ZwsK36BzcY
nope
Chevy Chase always whistled when he was playing Golf in Caddyshack.
“The New Gladiators” (1984)?
The entire movie can be viewed on YouTube and there is a scene of a whistling killer and his team whistling before killing the wife(?) of the main character. I posted it below and that scene starts at 11:45 of the video.
Well that sucks. Something went wrong but you can view the movie on YouTube under that title.
There’s a villain who whistles in the movie Hanna
https://en.wikipedia.org/wiki/Hanna_(film)
I’m not sure if that’s it, but here is a clip (it happens more than this in the movie)
The killer in “M” by Fritz Lang whistles before he kills.
In “The walking dead”, the Saviors were whistling while approaching to other groups, to scare them