You can't explain anything to Peppermint Patty because you never get to say anything.
8 seconds sound clip from the A Charlie Brown Thanksgiving movie soundboard.
You can hear this line at 00:05:59 in the Blu-ray version of the movie.
Quote context
[...]
- I think I'm losing control of the whole world.
- Now she's bringing Franklin too.
- Why don't you just call her back and explain it to her?
- You can't explain anything to Peppermint Patty because you never get to say anything.
- I'm doomed. Three guests for Thanksgiving and I'm not even going to be home.
- Peppermint Patty will hate me for the rest of my life.
- What time are you going over to your grandmother's, Charlie Brown?
- We're supposed to be there by 4:30.
[...]