As someone who works with preschool children, I'm often very deliberate about the things I say. I make sure every rhyme is pointed out, every letter that corresponds to someone's first name is traced, every opportunity for something new is used.
I've increasingly become very deliberate about the words I use when talking about behavior as well. I find myself repeating things like "When someone says no, you have to listen" and "Ask before you touch your friend." Sometimes my language is prompted by the language they use - if someone is complaining about hitting, then we talk about nice touching.
I do it because I want this language embedded in their vocabulary. I explicitly use no in this context because I want them to feel comfortable saying no (especially to their friends) and that when someone says no, it's respected.
I want them to know that you can't just touch another person's body without asking. One of my rules is that a kid has to ask before sitting in my lap. Partially, it's selfish. My legs get tired and fall asleep with too many kid bodies on them. But there's also that idea that my lap is mine alone and I make the decision if I want someone to sit there. If a kid walks up and sits down without asking, I make them stand up and ask me if they can sit there. Sometimes I say yes; everyone's happy (unless there's another kid competing for the lap. Long story). Sometimes I say no and suggest that they can sit right in front of me.
I'd like to think that these things stick with them, that they'll remember that they have to listen to another person's no. The unfortunate part about early childcare is that a lot of times, these kids won't remember us. I don't remember my preschool teachers. That's why it's so important that these basic concepts of bodily sovereignty are maintained from year to year.
I only hope that my no and respect for a no is remembered and thought of when they hear no again.