Adults love to say things like that, but kids know better.
5 seconds sound clip from the A Christmas Story (1983) movie soundboard.
You can hear this line at 00:20:54 in the Blu-ray version of the movie.
Quote context
[...]
- Now, I know that some of you put Flick up to this. But he has refused to say who.
- Now, don't you feel terrible? Don't you feel remorse for what you have done?
- Well, that's all I'm going to say about poor Flick.
- Adults love to say things like that, but kids know better.
- We knew darn well it was always better not to get caught.
- Now, boys and girls, I'm going to give you an assignment. I want you to write a theme.
[...]