Paint all the bars of soap in a house/residence/whatever with colorless nail polish (reserving, of course, one for oneself) then replacing them in the soapdishes. Those suckers won''t suds to save themselves.
Fill a manila envelope with shaving cream. Slide the open, top end of the envelope under the closed bedroom door. tHEN Stomp on the body of the envelope as hard as you can. The shaving cream bomb will cover everything in the room.