I had a similar one.  I was delivering post as a temp job one summer before uni and I knocked on the door to this flat and a woman answered the door, perfect 10, wearing what was basically a flannel, just jumped out of the shower.  She says 'oh, sorry.  I thought you were my sister'  I reply, 'no problem.  I uh, have a package for you' Sadly I was not invited in heh. 