Perhaps they should get some bullet resistant glass and line the floor with it (I'm thinking like at least 2 or 3 inches that can withstand some serious weight as well as .308 rounds fired downwards for posterity) and have a giant LCD monitor the size of the restroom floor underneath. Buff the glass to make it scratch resistant and to prevent boot scuffs. With the flick of a switch, the bartender or designated torturer can activate the floor monitor to display vortices, footage of falling from an airplane straight down, zombies grabbing at your feet, or maybe even a saltwater marsh with crocodile heads popping out...
Mount hidden Dolby THX-grade speakers in the ceilings to make the people inside think they are having auditory hallucinations. Maybe a sound studio in an adjoining room with mixing board and microphones to really pump some heavy shit in there when they are trying to handle their business. If you don't make them run out in fear with their pants around their ankles, you either aren't doing something right or they weren't drunk enough.