Sarcasm: This is the most common term, implying a mocking or ironic tone. You are being deliberately insincere, often with the intention of humor or to express disapproval.
Irony: Similar to sarcasm, but it doesn't necessarily involve mockery. It's more about a contrast between what is expected and what actually happens.
Hypocrisy: This refers to saying one thing but doing another, or holding beliefs that contradict one's actions.
Doublethink: This is a term coined by George Orwell in his novel *Nineteen Eighty-Four* to describe the ability to hold two contradictory beliefs simultaneously.
Reverse psychology: This is a technique used to get someone to do something by suggesting the opposite of what you want them to do.
Understatement: This is when you downplay the importance of something, often for humorous effect.
Euphemism: This is a polite way of saying something that is considered offensive or unpleasant.
The best word to use depends on the specific situation and the speaker's intention.