That's no ordinary man. He's going to be hard to track down.
3 seconds sound clip from Scooby-Doo, Where Are You! - Foul Play in Funland (S1E8).
You can hear this line at 00:10:32.515 in the Blu-ray version of the episode.
Quote context
[...]
- There he goes now into the Tunnel of Love, so we have to go into the tunnel after him.
- Row faster! We can catch him!
- There's something in that tunnel! It's him! He's swimming right at us!
- I thought we wanted to catch him.
- Like a torpedo, he's going to ram us!
- Thanks, Shaggy, but why don't we just walk out?
- That's no ordinary man. He's going to be hard to track down.
- He'd better look out I don't catch him. I'll make him pay for what he did to my hair.
- We can't go back, Scooby. Freddy said to look on this side of the park.
- Now, it's OK just to look for the torpedo man, as long as we don't find him.
- Huh? Oh, that. That's a real fun game, Scooby. Come on. I'll show you how it works.
[...]