And when this weirdo Indian attacked, I felt like a late-show rerun of Custer's Last Stand.

7 seconds sound clip from Scooby-Doo, Where Are You! - Decoy for a Dognapper (S1E5).

You can hear this line at 00:09:00.638 in the Blu-ray version of the episode.

Quote context

[...]

- You fool! That's not Bob Miller's champion Great Dane! How could you mistake this mutt for a show dog?

- Huh?

- Gee, boss. He was right where you said he'd be.

- Get this phony decoy out of here!

- But what will I do with him?

- Give him a ride down the mountain on the old handcar. By the time it stops, he'll be 20 miles away.

- Come on. Back in the crate.

- No! No! Uh-uh! Uh-uh!

- And when this weirdo Indian attacked, I felt like a late-show rerun of Custer's Last Stand.

- Are you sure it was a real Indian?

- Real? Why, when he waved that tomahawk, even my hair was scared.

- Well, no hoofprints in the road, but here's something I found. It's an authentic Indian relic, at least a thousand years old.

- I told you I thought he looked kind of ghostly.

- Hold it, gang. The transmitter on Scooby's collar is moving again, and it looks like it's heading for Indian Gap.

[...]