I remember listening to a lecture that said it was a valid alternate pronunciation (I guess like tomato/tomAHto).
I googled just now and found this:
“Aks” has origins in Old English and Germanic over a millennium ago, when it was a formal written form. In the first English Bible – the Coverdale Bible, from 1535 – Matthew 7:7 was written as “Axe and it shall be given you”, with royal approval.
Beyond written English, “aks” was also the typical pronunciation in England’s south and in the Midlands. “Ask”, meanwhile, was more prevalent in the north and it is the latter that became the standard pronunciation.
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In North America, “aks” (or “ax”) was widely used in New England and the southern and middle states. In the late 19th century, however, it became stereotyped as exclusive to African American English, in which it remains prevalent. American linguist John McWhorter considers it an “integral part of being a black American”.
Today, “aks” is also found in UK varieties of English, including Multicultural London English. This dialect, spoken mainly by people from ethnic minority backgrounds, came about through contact between different dialects of English and immigrant languages, including Caribbean Creoles, such as Jamaican Creole.
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Other languages have, of course, influenced Multicultural London English. But the English language has been in a constant state of flux for millennia, precisely as a result of contact with other languages. When we talk about “salad”, “beef” or the “government” we are not imitating French, despite the French origin of these words. They have simply become English words. In the same way, Multicultural London English is a fully formed dialect in its own right and “aks”, as with any other pronunciation in this and other English dialects, is in no way wrong.
