Ordering drinks is easy once you understand the system. But don't worry, in the big cities you will get by at most places speaking english, but you want to try anyway, right? After a bit of practicing you can mingle with the locals and shout "Boss. Teh Tarik. Satu Lagi." (Boss, give me another Tea)
Teh Tarik - Tea with condensed milk, sweet
Teh O Panas - same tea without ice
Teh O Limau Panas - Lemon Tea
The Panas (=hot) is optional, sometimes you will get the drinks with ice anyway so you add "panas" just to make sure.
If you want a cold drink you just add "ais" to it:
Teh Ais - Ice Tea with condensed milk
Teh O Ais - Ice Tea
Teh O Ais Limau - Lemon Ice Tea
Important: every drink in Malaysia is by default very (very) sweet. I would recommend to order everything with the magic words "kurang manis" (=less sweet):
Teh Ais Kurang Manis, Teh Tarik Kurang Manis .... and so on. It will still be sweet but not as bad. If you don't want sugar at all. Add "tak nak gula" (pronounce: ta na gula = don't want sugar).
If you liked the drink and want another one: "satu lagi" (=one more) will holding up the glass / cup.
Other drinks you will get anywhere: Nescafe and Milo (cacao drink), most of the times also "kopi" (=coffee). The sames rules apply to these drinks. Example:
Nescafe Tarik - Nescafe with condensed milk
Milo Ais - cocoa drink with Ice
2 popular cold drinks which are available everywhere:
Limau Ais - Lemon Juice (water, ice, freshly squeezed limes)
Ice Kosong - Ice Water (cheapest way to recharge - 20sen)
By the way, "tarik" means pull. The mean is used because the Teh will be "pulled" between to cups to mix it and cool it down.
In case you want to drink "to go" (here known as "take-away): ask for "bungkus".
Don't forget your "Terima Kasih" or even "Nandri" (tamil, if it is a indian place) which means thank you and you can be sure to be smiled at.