How old will you be tomorrow?

We've been talking about Timothy's birthday a lot in the last couple of weeks, and he knows he's going to be two (it's been his favorite number for a while, now, hehe). However, when he woke up from his nap today, we were talking and I asked him how old he was going to be tomorrow, and he said "Forty!" and started laughing hysterically. That kid just cracks me up!