"Indoor voices" and "gentle hands" - in fairness, I used both those phrases with DS when he was small.
DS is autistic and has dyspraxia, so is prone to being heavy-handed and accident-prone. He also has fairly high needs, so especially when he was younger, communication had to be precise and clear, while also keeping things simple. Using familiar phrases that he recognised was recommended by speech therapy to help him understand and process language.
So, for example, petting the dog - he wasn't hitting the dog, but due to his dyspraxia, he might be stroking the dog too hard. Gentle hands - often while putting my hand over his to model the correct behaviour - was the perfect phrase. I remember one time he wanted to hold a baby chick and I was bloody terrified he was going to squish the life out of it!! 🫣 So there were multiple repetitions of "remember! gentle hands!" while hovering over him 😂
"Stop hitting" wouldn't apply because he'd never hit an animal. Not ever. But accidentally clumsy as he wasn't paying proper attention to his hands? Yes!!
I have very rarely used "indoor voice" but can remember once or twice. "Be quiet" implies shutting up completely and "be quieter" could imply whispering. "Indoor voice" is very specific and conveys exactly what you mean.
I appreciate this thread isn't about SEN, but sometimes those phrases that sound annoying have very real and practical uses in children with communication difficulties.
I've never used "use your words" to an adult but when I've seen it used on here, it's generally meant to be patronising I think! Posters clearly get frustrated with people who have posted questions without having very basic, fundamental conversations with the people they need to, and expect Mumsnetters to be mindreaders 😂