hwat
The historical
pronunciation and an obsolete spelling of What (with the former Wh Digraph, excluding the words who and whom). The reason why it was pronounced like this was because of the fact that in Middle English, a swap of the
Anglo-Saxon {hw} to {wh} occurred (it was occasionally spelt as quat), but the older
Anglo-Saxon pronunciation stuck for centuries and didn't really die out until the 20th century in most English speaking areas. If a person were to pronounce what as "wat" in the 18th century or before, it would be seen as uneducated speech. However, this notion of thought faded out in the early 1800s. It is indeed the way that Hank Hill says what, something quite rare in the modern times.
An Example from
Anglo-Saxon: Hwæt! We Gardena in geardagum, þeodcyninga, þrym gefrunon, hu ða æþelingas ellen fremedon.
An Example from Early Middle
English: Auh lokeþ þurh hwat reisun. \
An Example from Hank Hill:
I'll tell you hwat