Its amazing that after so many years and viewings, Monty Python and the Holy Grail remains as fresh and funny as ever. The sheer idiocy and ridiculousness that runs rampant through the film and its actors cannot be denied its fair share of humor value. I know that this being one of the "kings" of the cult genre, its received a vocal backlash as many popular things are wont to receive. Yet, I say this here and I say this now: MP&HG rightly deserves every praise attributed to its comical genius, and then some.
King Arthur is having a 'ell of a day. Traveling throughout the land, he has to replace his horse with two coconut shells for the sound effect, and seeks in vain people to take him seriously. The Arthurian legend is turned on its head and its nostrils are raped in the Monty Python spirit. Mideval England is a certified nuthouse, with an inexplicable French castle, a Black Knight who refuses to give up even when all his limbs are lost, and the local peasants refuse to acknowledge Arthur's kinghood, choosing instead to live in a commune society.
Fortunately, Arthur manages to gather together a band of knights (from the cowardly Brave Sir Robin to the daft Sir Lancelot) and receives a quest from God (who finds it soooo depressing) to find the Holy Grail.
It's difficult to explain what, exactly, makes the Monty Python troupe so hysterical. Part of it has to do with their ability to talk silly things to death (as evidenced in the first scene, when two castle guards begin debating how swallows could migrate a coconut far north enough for Arthur to find). Most of it is a battle waged between two very silly and nonsensical lines, complete with straight faces...