Essentially, to porkpie someone is to ignore them (if intentional) or to simply not notice them.
The etymology of "porkpie" is as follows: In a weak attempt at improvised cockney rhyming slang, "porkpied" was used in place of "denied". That's it really. It sort of rhymes with denied.
Can be used as an
interjection, a noun, a verb.. even a way of life, if you're so inclined - making porkpie a valuable addition to anyone's
vocabulary.
Can be abbreviated to 'pied.
More experienced users of the word have been known to say it with an accompanying gesture - any formation of the hands, which alludes to the view through a cross-section of a porkpie, will do. A plan view of such a porkpie is generally
unacceptable, however, and can even be interpreted as an insult in some circles.