I have also on a couple of occations answered in my nightie/bathrobe/towell/the nude (not showing anything - wooden doors are wonderful thing) and let it be really clear that now is *not* a good time. "Sorry, I'm a little naked right now. But how about dinner on thursday?"
Now i know how you got your name you nutter ROFL
i am shocking for popping in on a couple of people without ringing... but only ones that i know dont care but if someone was unhappy with me popping in i would hope they said something to me. i would hate to find out later that i was annoying them.. good luck!!