An ounce of wit is worth a pound of argument

Then the small man suddenly ran after them and said:
"I want to get my haircut. I say, do you know a little shop anywhere where they cut hair properly? I keep on having my hair cut, but it keeps on growing again."
One of the tall men looked at him with the air of a pained naturalist.

It’s sarcasm, Josh.”

“Sarcasm?”

“It’s from the Greek, sarkasmos. To bite the lips. It means that you aren’t really saying what you mean, but people will get your point. I invented it, Bartholomew named it.”

“Well, if the village idiot named it, I’m sure it’s a good thing.”

“There you go, you got it.”

“Got what?”

“Sarcasm.”

“No, I meant it.”

“Sure you did.”

“Is that sarcasm?”

“Irony, I think.”

“What’s the difference?”

“I haven’t the slightest idea.”

“So you’re being ironic now, right?”

“No, I really don’t know.”

“Maybe you should ask the idiot.”

“Now you’ve got it.”

“What?”

“Sarcasm.

He had had much experience of physicians, and said 'the only way to keep your health is to eat what you don't want, drink what you don't like, and do what you'd druther not'.

Yeah you can have a word," said Harry savagely. "Good-bye.

That's the difference between irony and sarcasm. Irony can be spontaneous, while sarcasm requires volition. You have to create sarcasm.