This image shows one of the mounts ontop of a customised Boing-747 used to transport space shuttles (http://en.wikipedia.org/wiki/Shuttle_Carrier_Aircraft) from landing sites back to Kennedy Space center.

http://upload.wikimedia.org/wikipedia/en/f/f7/Shuttle_mounting_point.JPG

Well I thought it was funny.. :p

Maybe a previous incident led to this preventive measure. : )

"Brian, you've stuck it on the wrong way up again."