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

An original thought would crack your feeble skull like a thunderbolt, you craven vulture.

I can be most colorful and inventive when I am angry.

Do we still have to floss?" Tommy asked. "I mean, what's the point of being immortal if we have to floss?

He was a writer and words were his weapons.

Blessed are the dumbfucks.

Mr. Fresh looked up. "The book says if we don't do our jobs everything could go dark, become like the Underworld. I don't know what the Underworld is like, Mr. Asher, but I've caught some of the road show from there a couple of times, and I'm not interested in finding out. How 'bout you?" "Maybe it's Oakland," Charlie said. "What's Oakland?" "The Underworld." "Oakland is not the Underworld!" "The Tenderloin?" Charlie suggested.