"Miss Prinzo, I think I need to change my light bulb."
He proceeds to pretend to open his head, unscrews a lightbulb, screws a new one in, and closes his head...
"Oh! Now I understand!"
The best part: he did!
In all seriousness, the "click" or "light bulb" when students finally understand what they have been working on is my favorite part of teaching. Those are the moments I live for.