From the Wikipedia page  which lists various types.
Teh tarik (literally "pulled tea" or 拉茶 in Chinese) is a hot Indian milk tea beverage which can be commonly found in restaurants, outdoor stalls and kopi tiams in southeastern Asian countries like Malaysia and Singapore. Its name is derived from the pouring process of "pulling" the drink during preparation. It is made from black tea, condensed milk and evaporated milk.
The mixture is poured back and forth repeatedly between two vessels from a height, giving it a thick frothy top. This process cools the process fluid (tea) to optimal drinking temperatures, and helps to thoroughly mix the tea with the condensed milk. It is also done to give the tea a better flavor. This is often compared to the decantering of toddy to improve the flavor function.
An element of showmanship exists in the preparation of teh tarik. The ability to drag a long stream of tea above the heads of the patrons without giving them a shower is an amusing novelty for the locals and tourists alike.
In Malaysia, there are occasions where teh tarik brewers gather for competitions and performances to show their skills. Teh tarik has become recognised along with nasi lemak as part of the food and beverage heritage of Malaysia by the Malaysian government ministry.