The Westerner's Guide to Singlish
Don't use these on business trips, but your Singaporean friends may feel more comfortable if you use these when around them. Sometimes, this is the only way to break into Singaporean cliques. If you're planning a trip here, these will help you out alot.

Usually, the tone with which a Singaporean uses the suffix is a clear indication of his mood. These must be mastered over time, as the pronunciations are very different from those used in the english language (so it's really difficult to give a pronunciation guide)

dextrius' has a w/u on this, be it alive or be it dead, there are some points i feel he has missed out.

a) lah

there are 2 variants of this suffix. As a general rule, the louder and higher the tone, the more agitated/excited the person.

lah (deeper tone, drag the "a" sound a little) - usually used to express annoyance at subject of conversation. if he is relating a personal story, then subject is probably not you.
e.g. doe-wan lah! (I don't want it, isn't that obvious?)
e.g. not my fault lah! he beat me first okay! (it's not my fault, he hit me first!)
lah (firm tone) - use to give your statement a tone of finality
e.g. okay lah, settle lah (okay, the matter is settled then)

b) lor

lor (in a light tone)interchangeably used with "lah". Be careful, 'cos many Singaporeans tend to use "lor" to express sarcasm.
e.g. okay lor, my fault lor (my fault? yeah right)

c) liao

has 2 pronunciations, but both mean the same thing so it doesn't really matter. derived from the chinese word "liao", meaning "completed". Used to indicate that something is certain to happen.
e.g. wah, the exam so hard, i die liao lah (that paper was tough as hell, i'm sure to flunk)

note: "Liao" also means "additives". In this form, it is used as a word, not a suffix, and the two should not be mistaken for each other. In this latter context it sounds different and is usually not used at the end of the sentence.
e.g. i ask the char kway teow uncle to "jia liao" but he doe-wan, bloody *** (i asked the chef at the noodle stall to add more vegetables and meat, but he didn't want to. what a bloody ***)

d) leh

rough meaning: "didn't you know?". somewhat similar to hor.
e.g. that girl is mine leh. you touch her you die (that girl is mine, touch her and die)
e.g. dun anyhow touch touch leh, skali you break something must pay then you know (don't touch anything. if you break it you'll have to pay for it)

e) mah

rough meaning: "isn't it obvious? things are just that way". used interchangeably with "wat".
e.g. {in response to "how the hell does he manage to score As without studying?"} because he see beh smart mah (because he's so damn smart)
e.g. {why didn't you watch the movie with us yesterday?} because i kena grounded wat (because i've been grounded, duh)

f) meh

rough meaning: "do you need a reality check?".
e.g. you got catch such big fish meh? you lying right, i know you liddat wan lah (are you sure you caught such a big fish? you're lying right, i know you, you're always doing that)

g) har

used in queries, to affirm previous statement's accuracy. may be pronounced "ar" (they mean the same thing)
e.g. you just now say wheelock place 10pm har? (you just said "Wheelock Place 10pm", am i right?)

h) hor

hor (questioning tone) - similar to "har", but used to garner support for one's statement.
e.g. eh tom, you also saw him hor? he kick my cat and now he say he never (Tom, you saw him do it, didn't you? He kicked my cat and now he's trying to deny it)
hor (low/menacing tone, depending on intention) - rough meaning: "you got that clear, buddy?"
e.g. dun anyhow play play hor, wait i call my gang beat you up then you know (don't fool around with us, shrimp, or i'll call my gang down and beat you to pulp)
e.g. i go home first hor, must study for test tomolow (i'm going home first, i need to hit the books for tomorrow's exam)

i) man

(Listen to how they pronounce this before you use it, or you'll crack them up) - only used sarcastically.
e.g. yah man, i stole your wallet man (and i also raped your dog, blew up your car and kicked your girlfriend while i was at it)

j) xia

only used sarcastically. it means the same thing as lah.
e.g. {to punk skateboarders on the streets} waaaah, 360 ollie, zai xia. (whoa, a 360 ollie, somebody here thinks he's really skilled eh?)

Suffixes not used at the end of a sentence are meaningless; heed them not. That doesn't mean you shouldn't use them, though, just use them sparingly, and only right before the commas. Don't use these in text documents, though - that's just dumb.

Usually words in their own right, just used really often. Like "yo (brother)", only more varied.

a) wah/wah lau/wah lan/wah kao

may be followed by an "eh". used to express disbelief or amazement. You're better off not knowing what they really mean, since nobody uses them in the context of those meanings anymore.
e.g. wah lau eh, you borrowed 200 bucks from me yesterday and now you want to borrow 500 more? siao ah! (you just borrowed $200 from me yesterday and you want to borrow $50 more today? You're nuts, friend)

b) yah

meaning: yes. also used to receive calls on your handphone.
e.g. hello, is this pam? yah? why you call me? (yes, this is pam. why did you call?)
e.g. yah, i do wan. why, not happy issit? (yes, i did it. you have a problem with that?)

c) haiyah

a frustrated sigh. not pronounced the same way as one, though.
e.g. haiyah, why you so mah fan one? (*sigh* why are you so fussy?)

d) oi/eh

meaning: hey! (used in roughly the same way as "hey" too) both are sometimes used as greetings. e.g. eh, brother, how's your day?
e.g. oi, stop it lah (stop it)
e.g. eh, dun anyhow saysay my mother hor (don't you dare insinuate anything about my mother)

e) ta ma de

meaning: damn it, or damn (if used as a non-prefix).
e.g. tama de, the bus run off liao (damn, the bus left before i reached the stop)
e.g. wah kao, he's tamade strong (holy cow, he's damn strong)

Some words are not prefixes or suffixes, but are used on a regular basis. Get to know these.

Aiyoh - see "alamak"
Alamak - oh my gawd (not in amazement, in frustration).
e.g. alamak! why you pour the duck sauce into the soup?
Balek Kampong - go home
e.g. eh guys, i balek kampong first liao, see you tomorrow hor
Boh Lui - out of cash
e.g. sorry brother, i boh lui liao, cannot go watch movie
Brother - used by singaporeans, on singaporeans. You're better off using this on people you know well enough.
e.g. eh, brudder, you want kopi-o ?
Cham - pronouced "charm", but with a lower tone than the original english pronunciation. it means you're in trouble.
e.g. wah, cham liao, i left passport at home {and i'm at the immigration customs already}
Diam - stop
e.g. oi, diam lah, tamade guailan leh
Guai Lan - irritating
e.g. wahlao, the SAR-vivor rap damn bloody guailan leh
Haolian - to brag/show off/claim to be able to do something you cannot.
e.g. dun haolian lah, dunno how means dunno how lah, no need to show off wan.
Kaopeh - whine/complain. derived from "kao peh kao bu", literally "to cry out for your father and mother (to come and comfort you)"
e.g. oi, shaddup and stop kaopeh-ing lar
Siao - crazy. may also be used to express amazement.
e.g. oi, punch me for wat, you siao ar? e.g. siao! how the hell you do wan, so bloody hard?
Talk Cock (a.k.a. tokkok) - to make small talk, or to talk rubbish for the fun of it
e.g. aiyah, relax lar, he talk cock only, dun believe him can already.
Zai - skilled. Applies to any field: sports, academics, even money-earning power.
e.g. wah, how come he so zai wan, no need study also can get A

Of course, these words will not automatically make you a Singlish user. The key lies in the special grammar and sentence structures (which are similar to the Chinese and Malay language). To effectively learn Singlish, you have to forget everything you know about the English language. Singlish is short, efficient and Easterner-friendly. In Singapore, you'll find that close friends tend to communicate in Singlish because it's a much more intimate language. I'll try my best to introduce these rules to you, but the only way to really learn them is to speak to people who use them.

Rule 1: throw out unimportant words. you don't need 'the', 'is', and many others. use them sparingly.

Rule 2: don't worry about using words out of context or in the wrong tense, as long as it means approximately the same thing. The Singlish users are sarcastically impressed by proper use of English in the wrong place (waaaah, can speak the Queen's English xia?)

Rule 3: exaggerate all you want, especially if it's a story. not if it's an official report, or if it has possible negative implications. use "very" and "damn" often, and pronouce "very" as "vely"

e.g. President Bush is in trouble. He started 2 wars, hasn't killed Osama or Saddam, hasn't found the WMDs yet, and he's going to take on North Korea?
Bush siao lah, gone case liao. first he fight afghanistan, then he fight iraq, but haven't even touched Osama's beard or Saddam's moustache yet! he think he so bloody zai, but haven't even find any missile then want to talk so much cock. hao lian lar? i see how he going to fight kim jung il now, sure die wan.

slowly learn hor, dun rush! and remember to plactice!