- You're probably so high already you don't even know it.
- Probably.

4 seconds sound clip from the Caddyshack (1980) movie soundboard.

You can hear this line at 00:53:27.940 in the Blu-ray version of the movie.

Quote context

[...]

- But I want you to know about it. It's like acupressure, but it's acupuncture. The slightest prick and you wouldn't even know it...

- I'll kill you!

- No, no. I did not do that.

- See? You feel looser?

- Listen...

- I feel like a hundred dollars.

- Forget the massage, okay? And just kiss me, you fool.

- What kind of shit is this?

- It's the best, man. I got it from a Negro.

- You're probably so high already you don't even know it.

- Probably.

- Oh, wow.

- He looks like Dick Cavett.

- Hey, man, save me a toke.

- Oh, gotta do my doctor thing... Oh, ho ho, wow!

- All right, everybody. It's time to christen the sloop.

[...]