Lemons for lunch?

Today Nicholas & I were running errands and I thought we could have a nice lunch together. I ordered a cheese pizza for him, typically one of his favorites. While waiting for our lunch, his eyes fixated on the lemon on my water glass. He LOVES lemons. I finally gave it to him. Of course, he promptly dropped it and started throwing a fit. I asked the waitress for a bowl of lemons, so he ate 6 lemon slices and only 1 - 2 pieces of his pizza! Lemon is a fruit, right???