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

You think us fairies don’t understand sarcasm? We invented sarcasm.

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.

Can the sarcasm,' he said. 'Please, I always use fresh sarcasm, never canned.

Playful, positive sarcasm is different from negative mean sarcasm, and many people don't know the difference.

“Sarcasm: intellect on the offensive”

Sarcasm is waster on the young.

There is a great need for a sarcasm font.

The ego taunts truth with sarcasm.

Sarcasm is the new staircase to stardom.