Ohh... But wait! Perhaps if you'd say something only you would say, I'd know you're you.
7 seconds sound clip from the Boo to You Too! Winnie the Pooh movie soundboard.
You can hear this line at 00:10:52.041 in the Blu-ray version of the movie.
Quote context
[...]
- Hmm! Was it somethin' I said?
- There. Now you're s-s-safe and, uh, s-s-sound.
- It's me, them and, of course, us.
- Ohh... But wait! Perhaps if you'd say something only you would say, I'd know you're you.
- You are? Well, then, who am I?
- Are you quite all right, Piglet?
- You will be joining us for Halloween, won't you?
[...]