Cognomen Gaai (Gai 
, Gaius , ไก 
) , globally, is a common last name. The cognomen Gaai is characteristic of Monaco, where it is quite a common surname, Gambia, and Papua New Guinea, where it is quite a rare surname. In absolute terms, it is commonest in China, Nigeria, and India. Very seldom, Gaai is the forename as well as the last name.