When you get in, open the back door.
2 seconds sound clip from Scooby-Doo, Where Are You! - What a Night for a Knight (S1E1).
You can hear this line at 00:07:39.635 in the Blu-ray version of the episode.
Quote context
[...]
- Shaggy, you start up, and I'll get the jack out of the Mystery Machine.
- Right.
- Don't worry. Shaggy's the swingingest gymnast in school.
- When you get in, open the back door.
- Right. Watch me swing right in.
- Well, at least we know he's inside.
- Golly, this place sure is creepy at night.
- It's even creepy during the day.
[...]