It was not a customer. It was a critic.
4 seconds sound clip from the Ratatouille movie soundboard.
You can hear this line at 00:26:26 in the Blu-ray version of the movie.
Quote context
[...]
- You're fired! F-I-R-E-D! Fired!
- It was not a customer. It was a critic.
- Ego?
- Wait.
- What do you mean, Wait? You're the reason I'm in this mess.
- Someone is asking about your soup.
[...]