He had a good point.

A super sassy girl in class was really loudly talking to her friend across the room while I was trying to get everyone to settle down and get to work.

Girl, calling across the room: Ugh, my hair is so not big today!
Boy in front of her, exasperated, loud enough for her to hear: Well, your mouth is.

I stopped, stared at him, and burst out laughing.  The girl looked offended for 2.5 seconds and I told her there was no way she could be mad at that awesome of a burn.  She agreed, high-fived the kid in front of her, and the class had a good laugh together.