The art of insulting is a much under-estimated one. It wasn't long ago that a man was judged by his ability to insult others.

Over the years, a rich vocabulary of abuse has built up, providing a much needed range of insults. This huge choice is indeed important; without it, we would be reduced to a limited string of four-letter words, which is alas much the case for so many of us nowadays.
It is not that I would like to encourage abusive behaviour, but rather encourage the ability to speak one's mind articulately and to make use of originality and wit in our words.
So here are a few examples of past insults, which I hope will help you develop and enrich your knowledge of this unique art.

Harry S. Truman (on Richard Nixon):
"Richard Nixon is a no good lying bastard. He can lie out of both sides of his mouth at the same time and if he ever caught himself telling the truth, he'd lie just to keep his hand in."

Friedrich Nietzche:
"Woman was God's second mistake."

Cecil Beaton (on the mini-skirt):
"Never in the history of fashion has so little material been raised so high to reveal so much that needs to be covered so badly."

Doctor Johnson:
When told by a Scott: "Remember, Doctor, that God made Scotland", he replied: "Yes, sir. He also made hell."

Over the years, many famous people have become known for their ability to insult with style and wit. Groucho Marx, Winston Churchill, Oscar Wilde... But one of the all-time greats must have been Dorothy Parker...
After being told that a friend had broken her leg, she allegedly commented that she had probably done it... "Sliding down a barrister"
After having been told that Calvin Coolidge had died, she asked: "How can they tell?"

After being told by an ugly woman: "I just adore nature", famous comedian Groucho Marx replied: "That's loyalty, after what nature did to you."

Lady Astor once told Sir Winston Churchill: "If you were my husband, I'd poison your coffee." He replied: "If you were my wife, I'd drink it."

Of course, the ability to find the right words at the right time will not come overnight You need practise, and a lot of it. So here are a few more anonymous insults, for different occasions and for different places.
"Your speech was like a wheel. The longer the spoke, the greater the tire." "You have two lovely eyes, What a pity they don't match."
"I agree with you that success turned his head. It's just a pity it didn't finish the job and wring his neck."
"I didn't recognise you for a second. It was one of the happiest seconds rye ever spent."
"You dress like a bad photograph: overexposed and underdeveloped."

To finish, here are a couple of quick fire replies, which you may find come in quite useful:

"What's going on?"
"I am"

"Where in hell have I seen you?"
"What part of hell do you come from?"

"Where is this train going?"
"Straight down the tracks."

"I have something to tell you."
"Good, I have a couple of minutes. Why not tell me everything you know."