Again, if you are hard up for party themes, there are books availible that contains HUNDREDS of theme suggestions for parties, dances, mixers, etc. Most of them will have background props for sale, as well as give you ideas.
If you or your org has no creativity whatsoever, try that. As Bamboozled said, don't throw together some slap happy theme such as "Ghetto Fab" , and then play STUPID when the "fits hit the shan".
C'mon now......
__________________ "I don't know the key to success, but the key to failure is to try to please everyone."
, and then play STUPID when the "fits hit the shan". 
Hybrid Mode
