A zebra was sent on an exchange visit to an English farm - he was warmly welcomed and introduced to all the stock one by one
It first met the chickens - "You're strange looking birds' what do you do?"
"We're chickens - we lay eggs for the farm and eventually, our meat is sold to feed the people and our feathers used to stuff pillows"
"Very good" he moved on
Next he met the pigs - "We're pigs, the farmer tends and feeds us and in return, when we die, our meat is sold off and our skin is used for various things"
"Very commendable" - on to the sheep, a similar story
Then on to the cows
"We're cows - we give milk for the farmer which brings him a good living, we produce babies regularly which increase his prosperity, and at the end of our practical usefulness, we are sold at the local mart, our meat goes to feed the nation and our hides are used for the manufacture of clothes"
"you really are valuable creatures, aren't you ?"

Tiring a little and hungry, he wanders off to the outskirts of the farm to find somewhere to graze - in the far distance he spots an enormous, well endowed magnificent bull tethered in a field
Intrigued, he trots over - "I suppose your another cow ?"
"**** off - I'm a bull"
"What do you do ?"
"Get those ****** pyjamas off and I'll show you"
Jim