Irregardless is not a word.  Irrespective is a word.  Irrigardless will not become a word, it will not appear in the dictionary irrespective of now many times you say it.  Putting an “i” at the beginning of a word is what’s called a negative prefix.  It turns a word into its negative form.  Irresponsible, for example, is the opposite of responsible.  Irrespective means not respective, or to not take something into account.  I’ll use it in a sentence:

“I am going to keep writing mean thing about language irrespective of your feelings.”

Putting less on the end of a word is a negative suffix.  You take a word like gut, brain, thought, wit, and ad less to get gutless, brainless, thoughtless, or witless.  Oddly enough, all these words describe people who say irregardless.  It already means without regard.  Therefore to put an “i” at the beginning gives you a double negative.  Irregardless means “not without regard”.  I’ll use it in a sentence as if it were a real word:

“Irregardless of your plans for this friday, are you free for dinner?”

You see?  It’s stupid!  And that’s using it correctly, which no one ever has because we already have a word for “not without regard” and it works pretty well.  So stop saying it.  It means exactly the opposite of what you think it does and it’s hard to be more wrong than totally and completely wrong.

Just to put things in perspective: if you meant to go to the grocery store and you ended up at the cleaners, you were pretty wrong.  If you meant to go to the grocery store and you ended up at the bottom of the India Ocean you were really very wrong.  Saying irregardless is like being as wrong as it is possible to be wrong, like ending up in the farthest corner of the universe on your way to the grocery store.  So stop.