For one of the best comedies of the 70's, I would have to nominate one of my all time favorites:
"The Rutles, All You Need Is Cash"
For those who love "This Is Spinal Tap" and "Monte Python Holy Grail" (or "Life of Brian"), "The Rutles" is eggszactly what you would get if you melded those movies together (and "The Rutles" was created first, before "Spinal Tap" or any of the Monte Python movies). Eric Idle as the narrator throughout the movies is just awesome, as he delivers great lines one right after another. I was a huge fan of "The Beatles" music at the time, almost snobbishly so, so if a movie was going to parody my favorite band, it better be excellent or else. Guess what, "The Rutles" was not only excellent, it far exceeded everything I had hoped would make for a good comedy, that I even found humor in making fun of the Beatles because of it.
Some quotes:
Narrator: Stig, meanwhile, had hidden in the background so much that in 1969, a rumor went around that he was dead. He was supposed to have been killed in a flash fire at a waterbed shop and replaced by a plastic and wax replica from Madame Tusseaud's. Several so-called "facts" helped the emergence of this rumor. One: he never said anything publicly. Even as the "quiet one," he'd not said a word since 1966. Two: on the cover of their latest album, "Shabby Road," he is wearing no trousers, an Italian way of indicating death. Three: Nasty supposedly sings "I buried Stig" on "I Am The Waitress." In fact, he sings, "E burres stigano," which is very bad Spanish for "Have you a water buffalo?" Four: On the cover of the "Sergeant Rutter" album, Stig is leaning in the exact position of a dying Yeti, from the Rutland Book of the Dead. Five: If you sing the title of "Sergeant Rutter's Only Darts Club Band" backwards, it's supposed to sound very like "Stig has been dead for ages, honestly." In fact, it sounds uncannily like "Dnab Bulc Ylno S'rettur Tnaegres." Palpable nonsense.
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Narrator: In 1969, the Rutles made a triumphant appearance in America, playing live at Shea Stadium... named after the famous South American revolutionary: Shea Stadium.
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Of course, there is more, but if you've never seen "The Rutles", rent it and if you understand the inside jokes, you won't stop laughing. Another couple of movies I would recommend if you ever just feel like watching a silly movie or two is a couple of Woody Allen movies I personally think are his best:
1. What's Up Tiger Lilly - this is Allen's film debut, but he does not appear throughtout, only showing up to introduce the movie and provide some commentary in strategic places. What he did was re-dubb an actual Japanese spy film and worked in an entirely different plot: a movie about a top secret egg salad recipe. It is hilarious. When I was a kid, we would always repeat the fight scene of Phil Moskowitz (the Japanese spy) and Wing Fat. As they fight, Moskowitz keeps blarring out lines like "Take that you Spartan Dog... you Roman cow... you Spanish Fly!" Man, we could not stop laughing while acting out that scene. But my all time favorite line from the movie and one I exhausted throughout Jr. High, High School and on to college: "I'd call him a sadistic, hippophilic necrophile, but that would be beating a dead horse."
2. Bananas - this became my second favorite Allen film, only because the idea of Allen as a South American revolutionary was hillarious to me. Fielding Mellish is one of the all time classic Allen characters. My favorite line though was delivered by Esposito, the weird rebel leader: "From this day on, the official language of San Marcos will be Swedish. Silence! In addition to that, all citizens will be required to change their underwear every half-hour. Juan, you change with Pedro, Pedro you change with Jose... and so on. Underwear will be worn on the outside so we can check. Furthermore, all children under 16 years old are now... 16 years old!"