Sexual postion on a ship. Like Doggy Style
"Bent her over in front of the port holes last night" "Great view, love port holing"
The act of two people, male or female in any combination, rubbing their anus' together for the purpose of sexual gratification.
My wife makes me take a shower to remove my duck butter before long sessions of port holing.
After a long workout there is nothing quite as gratifying as the sweet surrender of port holing my best friend.