The last joke is a little intellectual: I have put a link to Wikipedia next to it which might help elucidate it for those of us without a head for physics.

Two cows stand in a field.
First cow: Are you worried about this Mad Cow Disease thats going round?
Second cow: Not really, I’m a chicken.
Source: PC Pro Interactive Forums

Q: Why did the chicken cross the road?
A: To get to the other side
Q: Why did the cow cross the road?
A: To get to the other side
Q: Why did the sheep cross the road?
A: To get to the other side
Q: Why did the farmer cross the road?
A: To get his animals back
Source: PC Pro Interactive Forums

Q: What do you get when you sit under a cow?
A: A pat on the head.
Source: Ice In Space Forums

Q: Why did the cow jump over the moon?
A: Because the farmer had cold hands.
Source: Ice In Space Forums

Q: When do you know it is time for the cows to go to sleep?
A: When it is pasture bedtime.
Source: Ice In Space Forums

Q: Why do cows lie down in the rain?
A: To keep each udder dry.
Source: Pure FM Forums

Q: What goes boo boo boo?
A: cow with a blocked nose.
Source: Digital Spy Forums

Q: What goes ‘oooooooooooooooh!’?
A: A cow with no lips.
Source: The CommanderBond.net Forums

Q: What do you get from a pampered cow?
A: Spoiled milk.
Source: JokeEmail.com

Q: What’s the difference between roast beef and pea soup?
A: Anyone can roast beef.
Source: JokeEmail.com

Q: Why did the cow ring its bell?
A: Because it’s horn didn’t work!!
Source: Wrexham Today Forums

Q: What do you get when you put a cow on a trampoline?
A: A milk shake.
Source: Some Christmas Cracker Jokes compiled by Owen Williams

Q: Where do cows go for a night out?
A: To the Mooooo-vies
Source: CPFC BBS Forums

Q: How do cows subtract?
A: With a cow-culator
Source: CPFC BBS Forums

Q: Where do cows go on holiday?
A: Moo York!
Source: Gamestyle Forum

Q: What do you get if you cross a cow, sheep, and a goat?
A: The milky baa kid!!!
Source: Natasha Bedingfield Forum

Q: What goes oom oom?
A: A cow walking backwards.
Source: CharlotteChurch.net Forums

Q: What game do cows play at parties?
A: Moosical chairs.
Source: CharlotteChurch.net Forums

Q: What do you get when you cross a cow with a duck?
A: Milk and quackers.
Source: CharlotteChurch.net Forums

Q: How do cows move house?
A: They call the Mooooovers.
Source: Gush Forums

Q: Why did the milking stool have only two legs?
A: Because the cow had the udder one.
Source: Christmas Cracker Jokes compiled by John Dubery.

Man in butcher’s shop: I bet you five quid you can’t reach the beef of that top shelf.
Butcher: No, the steaks are too high
Source: BBC Radio Lancashire (Google cached version)

Q: Why was the butcher worried?
A: His job was at steak!
Source: Observer Magazine

Q: What did the great explorer eat in the jungle?
A: Steak and pygmy pie.
Source: H2G2

First man: Do you want a game of Darts?
Second man: OK then.
First man:Nearest to bull starts.
Second man: Baa.
First man: Moo.
Second man: You’re closest!
Source: Zedge

Q: What do you call a tiny cow?
A: A Moo-on. *
Source: BioWare Forums

Lastly, I forgot to say happy new year yesterday, so merry Christmas and a happy new year!