You think you can do these things, but you can't, Nemo.
5 seconds sound clip from the Finding Nemo movie soundboard.
You can hear this line at 01:12:41 in the Blu-ray version of the movie.
Quote context
[...]
- How do I taste, Moby? Huh? Do I taste good?
- You tell him I'm not interested in being lunch.
- No. No more whale. You can't speak whale.
- You think you can do these things, but you can't, Nemo.
- He says it's time to let go. Everything's going to be all right.
- How do you know? How do you know something bad isn't going to happen?
- I don't!
[...]