Flying the pork starts happening after you leave the first pub for the night, either kicked out or because of closing time.
Being quite drunk, wandering the streets at night after everything was closed down and in search for a cab, but heading nowhere and just spinning around in circles, occasionally dropping some of your personal belongings or throwing yourself into the bushes if available.
Eventually you'll get to the next whiskey bar, but all the time spent from now until getting home counts as flying the pork around.
Using 'pig' instead of 'pork' is wrong and not meaningful in this context.
After the gig we were just flying the pork around when the police came and arrested us for allegedly causing nuisance and antisocial behavior.