MEN IN BLACK is a classic. From the theme song, to the aliens, to the "cricket" gun, people across the whole world recognize the famous special agents Kay and Jay.
Language is the biggest issue in the film. On the side is some comic violence (off-screen deaths of humans and aliens bursting into putty), a bit of scariness (aliens in human skin), and some vulgar sexual humor (some misunderstandings and questions; example: "do you know what I like to do sometimes late at night?" (That question isn't answered).)
It's fun and laugh-out-loud funny, and the acting is spot-on. A must-see, and it'll be okay for most teens, but I wouldn't take sensitive kids.