Yeah, my partner's family have a "family whistle" which is often employed to find one another. It's useful but also feels a little disrespectful.
It wasn't disrespectful at all. It was a great way to communicate over wider distances than is possible with regular voice, and in retrospect it was impressive how little translation it took for all of us kids to understand which meaning was being conveyed.
I whistled to an ex SO and they considered it disrespectful. I'm not sure I yet understand why it's disrespectful, not that I consider either opinion more or less correct. I just don't really understand that opinion.
Maybe someone can expand on it?