For my son's 9th b-day we hosted a "Backwards Party."  The invitations, banner and cake were all printed backwards.  The kids were told to arrive with their clothes on backwards. We had pancakes for dinner and pizza for breakfast (sleepover). The kids ate under the table. We had an obstacle course which was backwards then we awarded the prize to the slowest time.  The favorite part was the scavenger hunt in which all clues were given of course - you guessed it - sdrawkcab!! We even printed name tags for the kids with their names spelled backwards and they had to call each other by their new backwards name all night. We had a blast and the boys talked about the party for weeks.