Fart. This happens more often than you might think. I’ve learned to ignore it.
Say you were too busy to practice this week. This one never flies, ever. I always want to laugh a little, especially if the student is, like, 11 years old. My response is always something along the lines of, oh really, did you get time to watch TV this week? Play videogames? Yeah, I thought so. YOU DON’T KNOW WHAT BUSY IS!! You’re 11!!
Pick your nose. Quite a prevalent habit among younger children.
Cough at me, or on me. Only a few weeks ago I had a student cough directly onto my hand. Yes, it was gross. I maintained my composure and went and used some water-free hand sanitiser straight away. In hindsight I probably should have allowed myself to lose my shit a little. Always cover your mouth and/or turn away to cough, it’s just polite.
Play the piano while I’m talking. How rude. Please give me your attention when I am speaking to you!