For my daughters 8th birthday, we had a great idea of doing a "Crazy Mixed-Up Backwards" theme. We made colorful and wild invitations that said to wear a mixed up strange outfit. All the kids dressed up. When they entered the door we said " Goodbye" instead of "Hello". The first thing we did was eat cake, and then after we ate lunch. We warned them not to tell their parents about eating dessert first. We then played bobbing for apples with little funky prizes if they got an apple. They loved this game and lined up over and over again. Then we had a costume contest for 3rd 2nd and 1st places. The kids voted on who they wanted to win (not including themselves). We made sure nobody would have hard feelings if they didn't win. Then we decorated little frames ( cheap from IKEA) with glitter, paint stickers etc. etc.  We opened presents afterwards. Then when they had to leave we said "Hello" instead of "Goodbye".  All the children seemed to love the party and talked about it for a long time after.