XX and XY wall decals will bring delight as you watch your guests try to figure out which wall sticker is for ladies and which is for men! Stick these wall decals to your bathroom doors and let the fun commence!
Lighting signage for a hotel. This gave me another idea. If you placed 2 black lights in the positions of the normal lighting on this signage you could have the logo or type in UV o the wall enabling the black lights to highlight this.