Its when you are a private person, and well you are having sex, doggy style. You are shy and you are also curious.
While mid "The time between starting and when you finish", what ever that
urban dictionary term is. Well, at this time, you decide to conquer your shyness, and slip it
in the back door. Make it seem like it just slipped out, then full force it in there, now you have really come out... but she is curious herself and looks back to see whats going on... Since you are shy, and
embarrassed, you reflexively punch her in the face and scream "Mind Your Own Business!"
Cheers