Most of these are original, the rest were suggestions from the (ex) Pythonland forum

"Romans go home" in Latin is "'Romani Ite Domum"  NOT "Romanes Eunt Domus" (third person plural, present indicative.)
Ich bin ein holzfäller
Last year the government spent less on Silly Walks than it did on National Defence.
The Larch.
Wome is your fwend
There is no rule six.
  
Norwegian Blues stun easily
Charles Dikkens is a well-known Dutch author.
Some rabbits have a vicious streak a mile wide.
Never be rude to an Arab.
You can't cut down the tallest tree in the forest with a herring – it just can't be done (honest).
Pantomime horses make the best secret agents
  
Salmon mousse is bad for your health
Certain theories regarding the shape of the earth are disastrously wrong.
The most dangerous of animals is a clever sheep
Never underestimate the power of a bicycle repairman
If you become King, remember to brush up on your knowledge of swallows and gravity
Moose bites can be nasty.
  
You can't say (beep) on the radio
People aren't wearing enough hats
There is no such thing as a fish licence.
Lumberjacks are okay
Crucifixion's a doddle
When you need to identify a bishop, look for the tattoo on the back of its neck.
  
A witch will weigh the same as a duck because they both float and therefore are both made of wood.
The Sheep is not a creature of the air.
The Larch.
Life's a piece of shit when you look at it
If you can't think of a name for your pet, call it Eric
Coventry City has never won the English Football Cup
  
Never think twice about waking up the neighbour if you're an upper class twit
Philosophers like to drink
Always keep your cat confused
The Keeper of the Bridge of Death will ask you five questions (three questions)…
Don't even ask about the Camembert - you know the cat's eaten it
Nnnnnnnnooooooooooooo Pooftahs.
  
Not everyone likes SPAM
Nine out of ten British housewives can't tell Whizzo butter from a dead crab
Never trust strangers in suits of armour carrying chickens 
Albatrosses are bleedin' sea bird flavour.
Keep your eye out for 16-ton weights falling out of nowhere
Don't mention the dirty fork - it will all end in tears.
  
Be careful not to get squished by huge feet from the sky
It's important to learn to defend yourself from an attack with a piece of fruit.
The Larch.
When crossing the street, don't trust Keep Left signs
It is the inalienable right of any man to have the right to have children
My hovercraft is full of eels.
  
There is nothing quite as wonderful as money
Nobody expects the Spanish Inquisition.
Proust in his first book wrote about, wrote about (he wrote about) etc.
Blancmanges are better tennis players than Scotsmen.
It's important to know how not to be seen
The Larch.
  
European swallows don't migrate
Coconuts don’t migrate.
Tinny words are not as nice as woody ones 
Never trust a show to end when the end credits start rolling
The Horse Chestnut.
The earth is banana-shaped
  
... and most of all,
  
Always look on the bright side of life.
 

"Everything I Know In Life I Learned from Monty Python" is licensed under a Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales License.