While teachers generally don't like being interrupted or spoken back to, some smart alecks are so clever, they can't help but forgive them. A Reddit thread asked people to share the best smart-a** response they've heard from students in class, and these students were more "smart" then they were "a**." These one-liners were so perfect, they're remembered years later, unlike most of the things they heard in class.
Back when I taught first grade, we were doing a writing assignment about Thanksgiving. The kids had to draw a picture of their family celebrating Thanksgiving, and then write about it. One little girl drew the table and chairs, and that was all. I knew she just didn't feel like doing the work, so I tried to prompt her. I asked where the food and her family were, and she snapped right back with, "They're washing the dishes." Had to give her credit for coming up with a logical argument for not doing the work!-1robotsnowman