Two cups are wirelessly connected with each other. If the user holds one cup, it triggers soft glowing processes for the remote cup. When a person is drinking, the rim of the other cup begins to glow. Additionally, the cup displays the level of the liquid inside of the paired cup. If both owners take a sip at the same time, both cups are glowing at its maximum illumination. If a person shakes the cup, the other will vibrate. When used for social events, toasting two cups together activates them into a pair of Lover’s Cup.
Reference: Chung, H., Lee, C.-H. J., and Selker, T. 2006. Lover’s cups: Drinking Interfaces as New Communication Channels. In Extended Abstracts on Human Factors in Computing Systems (CHI’06). ACM Press, 375–380.
http://web.media.mit.edu/~jackylee/cups.htm