I remember thinking this movie was more of a pre-teen film than something appropriate for a six year old. But as others have pointed out, a lot of movies made today, Shrek being a good example, that are made for kids, have a lot more crass content than films made back when Goonies was first release. Asking the parents seems like the best advice.
If you have questions like this in the future, I recommend http://www.kids-in-mind.com. I use it to see what we’re getting into before we decide what our kids can see. http://www.screenit.com is also decent, but tends to be less comprehensive. Both are free, but are supported by subscriptions and advertisements, so contribute freely! I had hoped that one or the other of these two sites would have the Goonies rated on it, but it’s not there. I suspect it’s too old, and that they only rate more recent films.