When and how should I use multiple exclamation marks?

Now, I never do this, but in some few cases I have seen people use multiple exclamation (or question) marks like this:

Hey!!!

Is that orthographically correct? (Or just okay). In case it is, how many marks are grammatically allowed/accepted?

Solution 1:

'Multiple exclamation marks,' he went on, shaking his head, 'are a sure sign of a diseased mind.'

-- Eric, Terry Pratchett

More on this subject on the Discworld and Pratchett Wiki.

It's just for added emphasis. I do not believe it is strictly grammatically correct, but then using ALLCAPS is not, but people do that too, emphasis once again.

Solution 2:

It's fine in informal communication, email, poetry, and advertising headlines. Three would be most common. Two, four, or more is rarer.

It's never "officially" correct. The people who write books about how punctuation should be used in English tolerate only two levels of enthusiasm: not enthusiastic and enthusiastic. The idea that somebody might be very enthusiastic is too alarming to contemplate.

Solution 3:

Never.

At least not for grammatical purposes. More than one exclamation mark doesn't have any meaning. An exclamation doesn't get more "exclamationy" by more marks.

Of course, you could still use them, but the interpretation would be entirely up to the reader. Use of punctuation that doesn't have any grounds in grammar would be more like decoration.

I've seen people invent their own style of punctuation,,,like tripple commas,,,but that of course doesn't have any meaning either,,,it mostly makes the person look unstable...

Multiple exclamation marks are sometimes seen in leetspeek, often intermixed with intentional mistakes in the form of 1, one or eleven:

pwnd!!!!11!!111!one!!eleven!!!!

Solution 4:

"Keep your exclamation points under control. You are allowed no more than two or three per 100,000 words of prose. If you have a knack of playing with exclaimers the way Tom Wolfe does, you can throw them in by the handful." (Elmore Leonard)