It's from the 20th episode of the 3rd season of The Office. Here's the context:
Creed: When I went over Wednesday, for the spot-check, I got a call from Debbie Brown, saying she has an emergency dentist appointment. Dwight: Emergency dentist appointment. Creed: Now I’m told she told her manager she had the flu. I’m a trusting guy, but uh, I just wish Debbie Brown had been there. We would have caught this.