A dress that gradually disappears as you get a magic ball near to it? Yaishplease. That's exactly what Daan Roosegaarde, V2 Lab, and Maartje Dijkstra have created, using a flexible plastic material and radio frequency technology. Very pretty too:

Called Intimacy, the dress' smart fabric reacts to variations in the electric current, smoothly changing its opacity until it gets completely transparent—and viceversa. The change is controlled by a ball, which has an RF tag that gets detected by circuitry in the dress' collar. On a related note, this is what happens to my underpants whenever my fiancée gets close to me, with no RF tag involved whatsoever. [Roosegaarde and v2 via Styleguru via Fashion Tech]