Those white Christmas lights with the plastic covers shaped like cactii and flamingos and whatnot. Called sex lights because they're so effective for setting the mood. They're dim enough to disguise physical imperfections, but you can still discern the shape of your lover quite clearly. Also, they give off colored, not white light, which makes everything look a little more exotic. White light has the effect of making things look sterile and yellow light can make one's bedroom (or kitchen, or under the desk of one's cubicle..) resemble a library, living room, or other place people go to concentrate on non-sexual matters.