I watched this movie with my 22 year old son a couple of nights ago. It was the second time he saw it, and he thought I would enjoy it. We both laughed out loud, over and over. I liked the ending too. As others have posted, it has no profanity, no sexual stuff, just dialogue between characters. I seldom watch a movie from beginning to end, but I watched this one & listened carefully. I would recommend this one for a great break from reality.
I too, (as a 49 year old) watched it over the Christmas vacation with my 22, 19, & 17 year old kids. I had never heard of it before. I rarely sit through the entire movie of 90% of what they rent, but this one will definitely be a cult classic. The bicycle scene, the cow scene, and dance scene were hilarious, IMHO. If anyone can't laugh at those sophomoric scenes, then their escape hatch is puckered too tight. Loosen up! Anyone who can make a movie today for $400K and make $44 million and climbing gets my vote for business genius. Just like the Night of The Living Dead back in my days, it's a cult movie thing. I keep a DVD of NOTLD in my personal library and watch it every so often, and I'll watch it again and again. I may buy ND for my son for his birthday next week, then I can watch it again to see what I missed the first time. Sweet!