My freshman QB son complained to a ref when the defense was literally
calling out snap cadences, including "HUT . . .HUT!" — the ref told him the defense could call out whatever they want, even if they were trying to mimic the offensive cadence.
I could see my son having a lengthy discussion with the referee, and then shaking his head and walking back to the huddle. My son later asked me whether "disconcerting the snap" was a real penalty, because he'd seen it called in a BYU game. I assured him that it was and sent him rules at both the NCAA and high school level.
I was surprised (but not THAT surprised) that a high school referee didn't know this rule. The common response from defenses and defensive coaches it that the defense is just making their own calls, which they can do. But the officials are supposed to make a judgment call about the defense's calls and should absolutely penalize the defense if they believe the purpose of the defense's calls is to try to throw off the offense and cause false starts or confusion.