A variant of 'hows your father?' The origins of the phrase are obscure at best. To 'have a bit of hows your Minkton' implies that the individual in question has partaken in sexual activites that are far from what is considered simple love-making. Such complex maneuvres as inverted fisting, mongolian hate slamming and the 'human sock' would be considered some of the tamer moves used during a session.
John: How about a bit of hows your Minkton?
Stacey: You sick bastard! Ok then.
Additional note: My house is your house and your house is Monkhouse.