There seems to be a lot of dirty jokes that go just a little over the kids' heads in this movie...
* In the beginning, when Skiff is warning Lem of the upcoming alien invasion, he states that he already "has protection against the alien's favorite form of analyzation- the probe". He gives Lem a cork and gestures, ahem, where to put it, to which Lem responds with "Yeah, yeah, I get it" before he can say the word itself. Then he says, "Oh wait, I already used that one!", and Lem's reaction? Pretty much shock and disgust and he drops the cork immediately. Really, that entire scene is pretty much made out of this.
* After the TV advert for toothpaste, the one dressed up as the toothpaste itself praises the guy dressed as a toothbrush. He responds that he's much better at playing the suppository.
* When Neera comes out of her house, and Lem is prepared to make his move, his father tells him: "Go on, soldier, take that hill!" and chuckles.
* A police officer watches a woman walk by, particularly her chest, and the woman tells him to "Keep his eyes on the aliens."
* When Skiff bursts in on Chuck teaching Lem to woo girls, they look as though they are about to kiss and Skiff shouts: "The cork! The cork!"
* Near the end when a blanket falls off a naked Chuck as he stands up, Skiff remarks "That's an odd place for his antennae."
* When Chuck first introduces himself to Lem, Lem extends the S while attempting to say "Astronaut". Chuck's reaction makes it clear that this is intentional.
* "Okay, either your name is Lem, [[HoYay or you want to mate with me]]".
** Even funnier for a dane, as in Denmark, Lem is slang for penis.