Nuts and Bolts: irony punctuation.

 Irony punctuation is, yes, that's right, well done, punctuation which indicates irony.

Is it necessary?

No, or it would have caught on long ago.

There have, after all, been enough attempts at popularising a sign to flag up irony. In 1668 John Wilkins suggested an upside-down question mark; in 1841 the Belgian printer suggested a thing like an upward-pointing arrow; in 1899 the French poet Alcanter de Brahm's suggestion looked more or less like a mirror-image question mark. 

Then there was Hervé Brazin, who used the Greek letter psi with a dot underneath it: 

In more modern times,Tom Driberg was all for italics that slope backwards.

Nowadays people will sometimes type

 /sarc 

or 

/s 

after a statement that's intended to be sarcastic, and there are those who have used 

[?] 

in the same way.

Then there's the 

:^) 

emoticon, which I rather like (but only because it reminds me of Worzel Gummidge); the combination 

(? 

the word kappa; the tilde; or even alternate upper and lower case lettering.

Wikipedia claims that some people are using a small picture of SpongeBob Squarepants dressed as a chicken for the same purpose. 

But that statement itself must surely be ironic.

Nuts and Bolts: irony marks. Are unnecessary. The word irony comes from the Latin word ironia, from the Greek eirōn, dissembler, from eirein, to speak.