This movie is kind of a guilty pleasure of mine, but if it came out today it would definately be PG-13. Mild to moderate swearing shows up like every 5 minutes including one scene where variations on the phrase "blow it out of your @$$" was said a dozen or so times.
There is also some mild sexual discussion such as a lady describing pleasuring herself with a washing machine.
The Great Outdoors is a funny movie that my dad recommended for me. We bought it at Blockbuster and we were surprised at the amount of language. There is everything but F-words in this movie. Also, in the beginning there is a scene of foreplay that is interrupted by Aykroyd's family. There is some teen kissing, too. It is a VERY funny movie, but be aware of the language before you let kids watch this movie.
It was a very stupid movie, but I saw it when I was 9 and didn't really care or anything. There is one scene where a couple is hugging and the husband unclips her bra, which is shown hanging off her finger when a group of people come in. A man talks about twin sisters as 'expecting their heads to spin around and for them to puke pea soup', obviously referring to the Exorcist.