He seems pretty definite, Jim.
2 seconds sound clip from the Attack of the Crab Monsters (1957) movie soundboard.
You can hear this line at 00:18:29.689 in the DVD version of the movie.
Quote context
[...]
- Oh, hold it. That ridge will drop right off.
- But only this morning I came along this path on my way to the beach.
- You mean this pit wasn't here before?
- It has only appeared in the last 20 minutes.
- And it's at least 50 feet deep.
- No.
- Why not?
- He seems pretty definite, Jim.
- Is he right about a cave-in?
- He could be, assuming this was caused by a disturbance.
- Why, it's glazed as though it had been fired in a kiln.
- Come on, honey, let's go back to the house.
[...]