What's going on here? What are you trying to do to my little sister?
— Charlie Brown (Peter Robbins)
4 seconds sound clip from the It's the Great Pumpkin, Charlie Brown (1966) movie soundboard.
You can hear this line at 00:06:40.380 in the Blu-ray version of the movie.
Quote context
[...]
- I'm writing to the Great Pumpkin.
- What's going on here? What are you trying to do to my little sister?
- Hey! I got an invitation to a Halloween party!
- Is the invitation to Violet's party, Charlie Brown?
- Yes. It's the first time I've ever been invited to a party.
[...]