The most subtle thing you can do to show you're frustrated with a student

This is inspired by a post I recently made and one of the comments was that it's often the little subtle things we do that really upset kids. So use this thread to share your favourite little things to do to show you're irritated with a student. <br><br>For context, I'm a primary school teacher in the UK so most of the posts on this will be from a primary setting.<br><br>edit: to clarify, this is not "let's all bully the kids" I've never seen that suggested on this subreddit. This is things you do to let the kids know you're not happy with them and that they should be on their best behaviour.