My town has been twinned with Disney World!  

Sister cities, also known as town twinning, is an agreement between towns, cities and even counties in geographically and politically distinct areas to promote cultural and commercial ties. In the United Kingdom the term twin towns is most commonly used, generally referring to town-twinning with Europe, differentiating with the term sister cities which is used for twinnings with the USA. In Europe, a variety of terms are used; most commonly twin towns, but partnership towns, partner towns and friendship towns, are also used. Germany uses Partnerstadt (Partner Town/City), France uses Ville Jumelée (Twinned Town/City).North America, South Asia, Australasia and Asia generally use the term sister cities. In the former Soviet Bloc countries twin towns is used, as well as the term brother cities which is also used on occasion.[1]

Sometimes other government bodies enter into a "twinning" relationship, such as the agreement between the provinces of Hainan in China and Jeju-do in South Korea, or between Chinatown, Washington, D.C. and Beijing.

The Douzelage is a town twinning association with one town from each of the member states of the European Union.[2]

I got this from wikipedia as I thought it may explain it better than I could!