My favourite is the Dennis Moore sketch (hand over your lupins) about a highway robber of the 18th century the full sketch can be found here http://www.jumpstation.ca/recroom/comedy/python/dennis.html but I thought you might like a snippet of the sketch to read before going there)
Holy Grail Bedevere: What also floats in water? Peasants: Bread Apples Very small rocks Cider Gravey Cherries Mud Churches Lead King Arthur: A Duck!
Holy Grail French Guard So you think you can outwit us french folk with your silly knees bent running about advancing behaviour? I wave my private parts at your aunties, you cheesey lot of second hand electric donkey bottom biters!
Hitler in England (Mr. Hilter) Great Cleese - Nuremburg speech moment on a balcony! sorry, didn't notice it was the room for sketches
"Is it a stockbroker?!... Is it a quantity surveyor?!... Is it a church warden?!... NO!! IT'S BICYCLE REPAIR MAN!!"
I found a Monty Python script site while I was at college, and spent a few hours in the IT room giggling silently to myself. They all thought I was weird I'd have to say either Arthur "Two Sheds" Jackson or the one with the penguin on top of the old lady's TV exploding.
Nobody expects the Spanish Inquisition sketch has to be up there. But, if it counts, I don't think anything beats Life of Brian....
Do coconuts migrate? Well, do they? Or were they carried by swallows? And If so were they African or European?