A swimsuit is an item of clothing designed to be worn for swimming. Swimsuits can be skin-tight or loosely fitting and range from garments designed to preserve as much modesty as possible to garments designed to reveal as much of the body as possible without actual nudity. They are often lined with a fabric that prevents them from becoming transparent when wet.
The effect of seening someone in a swimsuit, underclothes, naked, ect. then losing the ability to look them in the eye, look at them the same or look at them with a straight face again.