what is sarcasm? In what situations do people use sarcasm?

Sarcasm is way of using words that are the opposite of what you mean in order to be unpleasant to sb or to make fun of them. People usually use sarcasm in two situations.

How can you tell if someone is being sarcastic? What clues can you use?

It is easy to find someone who is using sarcasm, such as facial express, body lanugage, what he is saying and so on.

Low, flat intonation OR exaggerated intonation

an expressionless face OR exaggerated expressions

extreme language: fantastic, incredible, gorgeous, etc.

conflictiong verbal and non-verbal messages

Which of the technigques do you think would be the most difficult to recognise? Why?