The kid's not kidding, Ma. There's a tunnel down there.
5 seconds sound clip from the The Goonies movie soundboard.
You can hear this line at 00:59:13 in the Blu-ray version of the movie.
Quote context
[...]
- I'm beginning to like this kid, Ma.
- No, I'm too young! No! I wanna play the violin! Not my hand!
- Now, do I get the truth? Do I get the truth, or do you get juiced?
- The kid's not kidding, Ma. There's a tunnel down there.
- Watch your hair! They're going for the hair!
- Hey, Mikey, if you can hear me, run!
- Run! They're coming after you!
- Hey, you guys, if we keep going this far down, we'll reach China.
[...]