While browsing the net for fun, I discovered the Ping Pong Door, which reminded me of my childhood, when I used to play ping pong with my brother on the dining table, causing our mother to go crazy. If we only had such a door, like this one designed by Tobias Franzel, everybody would have been happier: us, our mother and our table (which got severe damages from all those hits):

ping pong door

The only drawbacks of this table-door are that it is a little bit too narrow to play double, and you have to decorate one of the rooms to match its green side (green being the color I sincerely hate).

Would you like to join me for a ping-pong game through the doorway?