The first time a negative behaviour creeps into a client relationship I tend to approach it with a 'sarcastic joke' to lighten the conflict of it a bit so sort of playing off of Sunflower something along the lines 'Wow so glad you feel comfortable enough to just walk in the house but just a heads up that my spouse likes to air the boys after daycare hours so in the future might be best to knock to avoid any awkward encounters' .... if a client did not GET the seriousness of the request after that first time the next time the HAMMER would drop with a 'Hey tried to approach this with humor the first time while giving you the benefit of the doubt it was just a momentary lapse in judgement - however I now feel the need to address this head on - this is my HOME and you may not enter it without knocking and waiting to be 'invited' into it. I need you to respect that otherwise we are going to have a problem with service moving forward."