One rarely channel surfs past “Monty Python and the Holy Grail” when it pops up on broadcast or cable TV. Renewing your acquiantance with the funniest movie of 1975 and probably the silliest movie ever made is a guilty pleasure few fans turn down.

I hadn’t seen it in a theater since what I think was its last “anniversary” or “new DVD/BluRay” re-release back around 2004. With an “Evening with John Cleese” and “The Holy Grail” rolling round, I relished the chance to see it on the big screen again.

Some sight gags and wacky-phonetic/Saxon English opening credits jokes you expect to play better in a theater, and with an audience. But what struck me the most this time around is how cheap it doesn’t look.

Sure, the film stock isn’t the best, the effects primitive enough to point out as a punch line.

“It’s only a model!”

But Hazel Pethig’s costumes seem period perfect, even if the “chain mail” was loops of wool. And Roy Forge Smith’s production design, with input from Python cartoonist turned co-director Terry Gilliam, looks positively archeological.

I don’t know if it’s the nearly perpetually gray skies over the primitive Scottish locations, the fake fog or the very real mud that permeates many a scene, especially early ones. But the entire affair looks like a documentary-real absurdist farce by Samuel Beckett acted-out by the greatest British clowns of their day.

If you know the film you’ve heard the stories — repeated by Cleese at that screening — of the way it was filmed for a pittance, that the “coconuts” were an exceptionally clever way of avoiding the expense of renting horses, teaching the cast to ride them and the like.

But by the time Tim the Enchanter (one of several characters played by Cleese) is pointing his fire-breathing staff and setting off explosions late in the third act, I was muttering “Wow, this is something to see.”

Cliffs and caves and castles and mud-mired villages and sylvan forests ruined by assorted rival “knights” who challenge King Arthur and his motley crew at every turn are so inviting — save for the mud — that they impact Scottish tourism and one particular castle location to this very day.

The story — Arthur, played by Graham Chapman at his straight-man sternest, and his faithful servant/coconut-clacking pack mule Patsy (Gilliam, REALLY into the part) make their way across this corner of Britain, trying to convince the locals that A) he really is king, B) they really are Britons and C) that his authority was ordained by God and “The Lady in the Lake” who handed him the sword Excalibur.

“Listen, strange women lyin’ in ponds distributin’ swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony.”

Knights such as Sir Bedevere (Co-director Terry Jones), Sir Lancelot (Cleese again), Sir Galahad the Pure (Michael Palin, of course) and the “not so brave” Sir Robin (Eric Idle) join the traveling retinue, which avoids Camelot and its Round Table as “a silly place,” as Arthur accepts a quest from the Almighty, that he and they seek the Holy Grail.

The many set-pieces here, sketches built around Arthur or this or that knight’s encounters with figures prosaic and mythic, still induce giggles — from the randy sisters of Castle Anthrax, led by twins Zoot and Dingo (Python’s go-to laugh lady Carol Cleveland) who long to corrupt “pure” Sir Galahad, the quest for “shrubbery,” the hilariously dim-witted witch trial featuring Cleese’s then-wife and future “Fawlty Towers” collaborator Connie Booth to a “damsel” rescue Lancelot slaughters his way to, only to realize a sissy Prince Herbert (Jones again) is the one who requires rescuing.

Cleese’s glorious bit of French-accented taunting from castle battlements may offer the most quotable lines in this most quotably hilarious cult comedy.

“You don’t frighten us, English peeg-dogs. Go and boil yourrrrr bottoms, you sons of a seeelly person. I blow my nose at you, so-called ‘Arthur King,’ you and all your silly English Kuh-niggets!”

Cleese’s many comic creations — the stubborn Black Knight who will not yield, calling each limb lost in a duel with Arthur “a flesh wound,” Tim the wild-eyed wizard — make him the stand-out in the picture, amusing in every guise.

But from the first time I saw it until now, it’s been obvious to me that Chapman carries it. His self-serious Arthur, under-reacting, reacting and over-reacting to the “silly” going on all around him, was pitch perfect here, and in the later “Life of Brian.”

Chapman’s Arthur is a version of his conservative man/military man stentorian figures who’d march into a sketch or a shot with an officious, “Right. Damned silly. That’ll be enough of that” variations, the serious man taken aback by the lunacy going on around him on the TV series.

The gay member of the troupe was its best straight man. He is the contrast to the absurdism, arguing about how coconuts could have journeyed to Britain, trying to get the attention of a “French” castle, in England over 100 years before the Norman Conquest.

“Go and tell your master that we have been charged by God with a sacred quest. If he will give us food and shelter for the night, he can join us in our quest for the Holy Grail!”

The production design is the buy-in. Cleese, Palin, and to a lesser degree Jones and Idle, bring the surrealism. But Chapman, with the perfect voice for a stern, schoolmaster lecture on the Dark Ages, pre-history Britain and the Arthurian legend, is the credibility.

Add them together and “Monty Python and the Holy Grail” remains one of the great see-it-with-an-audience cult comedies, riotously funny at times, grimly goofy at others, and muddy and bloody almost all the way through.

And sparrows to catapults, coconuts to killer rabbits, “Bring out yer dead” to “Run away!” the “Grail” almost never looks like the comic-thrills-made-on-the-cheap classic that it is.

Rating: PG, a little innuendo, comically bloody violence, profanity

Cast: Graham Chapman, John Cleese, Terry Jones, Michael Palin, Eric Idle and Terry Gilliam, with Carol Cleveland, Connie Booth, John Young, Rita Davies, Bee Duffell and Neil Innes.

Credits: Directed by Terry Gilliam and Terry Jones, scripted by Graham Chapman, John Cleese, Michael Palin, Eric Idle, Terry Jones and Terry Gilliam.

Running time: 1:31