Pie your R.A. event. You can charge participants depending on how close they are to the RA (or even hall director). The closer to the person, the more money you can charge. The money collected can be donated to a cause of your choice. Be sure to provide easy clean up solutions for the staff involved (showering right afterwards and a way to get to a shower without dipping everyone) and the area the event is held.
Giant Connect Four! Take a shower curtain, spray paint it yellow and leave "holes" for the game pieces. Grab some plastic plates from the dollar tree and throw on Velcro on the back of the plates and where the holes are, then use Velcro to hang it from the wall each time you want to play.