The Godfather. Everyone knows what it is, and everyone's made references to it some time or another. I remember seeing it in the top shelf of a video cabinet at my friend's house as a child. The videos on that shelf were of the sort of Lethal Weapon and The Terminator, all movies that I knew about as a child but have gotten a chance to fully enjoy only recently, and boy, is The Godfather enjoyable.
I'm not one to spoil stories for other people, despite my previous track record on video games that my cousins can attest to, so if you haven't seen this movie yet, immediately do so, but only after reading this spoiler-free blog post. In a non-spoilery summary, the story is a testament to corrupt American business dealings in the first half of the twentieth century organized by underground (Italian) mafia families. These "Five Families" basically pull the strings of all legitimate organizations through non-legitimate means. The movie places great emphasis this concept of family and explores what it means to defend family despite, or maybe in junction with, many adult and moral themes.
After much epicness/confusion ensues, the story concludes with a new head of the Corleone family, setting the plot for The Godfather, Part II. I need to see that. Very soon. Just like you need to see this movie, even if you've already seen it. Watch it again and again and again, or else the Italian mafia will come after you.
P.S. That last paragraph didn't exist eight seconds ago. I just really needed to get this thing off the back of my mind. Legitimate blog posts coming soon! Maybe.