N

NA BEH/NA Bu/Ni Na BEH/ NI NA BU
Various contractions of "Ka Ni Na Bu Chao Chee Bye".

NABEDOUS (nah-ber-dous)
Adjective describing something as possessing that "na beh" quality.
"Eh, don't be so nabedous, can or not?"

N.A.T.O. (nay-toh)
A local acronym standing for "No Action, Talk Only", which probably originated in the Army.  Everyone is labelled this at some point in their career.
"Aiyah, don't waste time with him, he damn NATO one."

Neh’mine
A contraction of ”never mind”.  Can be used aggressively, as a threat.
1.  “If you’re too busy to help me, neh’mine.” It’s alright  if you’re too busy to help me.
2.  “I always help you and now you sabo me like that? Neh’mine!”   

NEH NEH POK
Hokkien for nipples.
"Wah lau, his T-shirt is so tight, you can see his bloody neh neh pok."

NENEK (neh-neh')
Not your peranakan grandmother, this is merely the helicopter pronunciation of "grenade".
"Wah lau, the nenek essploded too early and he concuss."

NEVER SEE BEFORE, IS IT?
A belligerent expression similar to "What's the big deal?" 
"So what if I'm smoking! Never see before is it?"

NGEOW
Hokkien for 'cat'. Describes someone who is very malicious, nitpicky or tries to find fault. 
"That sergeant dem ngeow one, no point go and sah kah him."

NI NAO HIAH/NAO HIAH
A curious term.  It seems to originate from the Hokkien term "Lao Hiah", which means "old brother", but pronounced this way, it seems to have become a profanity.
"You steal my girlfriend and now you want to borrow money? Ni nao hiah!"

NO SOUND NO PICTURE (contributed by Karen Toh)
A no-show.
"Eh, I thought he was supposed to be here an hour ago? You mean he still no sound no picture ah?"

NONGSNGSE (nong-sngs)
The proper pronunciation of "nonsense".
"This TalkingCock wep site, ah, is full of nongsngse one."

NOR CHAT
The local pronunciation of "not yet"
1. Beng: "Eh, you finish your homework or not?"
    Seng: "Nor chat." 

NOT SAY I SAY WHAT
A very common way of prefacing a statement that could be controversial or sensitive. The English equivalent would be, “This might just be my own opinion, but…” or “I’m not sure, but…”
“Not say I say what ah, but Ah Lian’s dressing is si beh obiang.” 

O

O.C.B.C. (contributed by Char Kuey Teow)
Acronym standing for "Overseas Chinese, Bukan Chinah", i.e. a Chinese person who is not sufficiently Chinese.
"All those bananas at the Cricket Club, ah, all OCBC one."
See also: Keng Chio Kia

OBIANG
To be embarrassingly out of fashion.
“Check out his bell-bottoms! Super obiang, man!”
See also: Orbit

OCCIFER (contributed by AA)
Deliberate mispronunciation by Hokkien Pengs of "Officer".
"Sir, not say I say what ah, but you cho occifer damn tua kee meh?" (Sir, pardon my impudence, but what's the big deal about being an officer?)  

OFF (1)
A term normally used during national service to denote “time-off”.  An “off” is a sanctioned release from duties, given on an ad-hoc basis, as opposed to “leave”, which is a statutory entitlement.
1.  Beng:  “Eh, where are you going?”
     Seng:  “I got one off today.”
2.  “I’m not on leave. I’m on off.” 

OFF (2)
Economical verb meaning to turn or shut something off.
“Please off the light.”
See also: On. 

OFF DAY
Day off.
“Today is my off day.”   

OLENG JOO
The correct pronunciation of "orange juice".

ON  (1)
Economical verb meaning to turn something on.
“Please on the light.”
See also: Off. 

ON (2)
Shares the same meaning and is used in the same way as “On the Ball” and “Siao On”, and is probably a contraction of either.
See also: On the Ball; Siao On. 

ON (3)
An enthusiastic assent to participate in an agreeable activity.
“Play football tomorrow? On, man!” 

ON THE BALL
Someone who’s on top of things or is very hardworking and detail oriented. Perhaps excessively so.
“Johnny never leaves the office until 9. He’s damn on the ball, man.”  

ONE
Yet another Singlish tag, similar in use to "lah", but which almost always follow a word which is some sort of attribute. This probably stems from words such as "de" in Mandarin and "eh" in Hokkien.
1.  “Why you so stupid one?”
2.  “Aiyah, he’s like that one, lah.”

ONE KIND (contributed by Terry How)
Contraction of the phrase "one of a kind"…usually used pejoratively.
"Ah Seng this kind of friend, damn one kind one! Everytime go out he say no money, ask me pay first!"

OOH SAY (contributed by AA)
The opposite of "Boh Say".
See: Boh Say

OOH YIAH BOH? (contributed by Benny)
Hokkien phrase meaning, "is it for real?" or "Are you sure?"
Ah Lian: "Eh, I heard Ah Seng pass his 'O' lebber..."
Ah Beng: "Ooh yia boh?"

OR-BI-GOOD (contributed by Roger Ng)
Not the name of a Singaporean Jedi Knight, this is a Singlish term which is used to to express that someone deserves his current predicament.  Often said while making an action like a chicken flapping its wing, with arm curled, and the elbow hitting one's side.  Of unknown derivation.
"Ah Seng is such a ya-ya papaya. Now he fail his 'N' Level, or-bi-good!"

OR-EE-OR-EE-OR TARZAN BOH CHENG KOR (contributed by Edwin)
Derived from Johnny Weismuller's version of Tarzan's call, this is a cry used by older brothers to tease their younger brothers (2-4 years old) when they come out of the shower butt-naked. Literally, "Or-ee-or-ee-or, tarzan has no pants on!"

OR KWEE KENG
The Hokkien term for "brothel", it literally means "black turtle house".

ORANG PUTIH (oh-rahng poo-tay)
Malay term literally meaning, “white people”.  Describes Caucasians.
See also: Ang Mor; Mat Salleh. 

ORBIT
A term of uncertain provenance, meaning “extremely obiang”.  Possibly a deliberate mispronunciation of “off-beat”.  May also connote being “out of this world”.
“Are those spandex tights he’s wearing? Orbit or what?”
See also: Obiang. 

OREDDY
The proper pronunciation of “already”.   

ORH (contributed by AA)
Popular singlish contraction for "Oh, I see."
"Orh.... so it's behind your house, issit?"
See also: Han Tse

ORH PEE SAI (contribution by Chen Zhiwei)
Hokkien for "picking one's nose".
"Ah Wai always got nothing better to do than to Orh Pee Sai."

OSO CAN (ohso-can) (contributed by Mark)
A crude pronunciation of the words "also can," and is usually found at  the  end of sentences. Means "this is okay with me," or "this can also be  done."  The norm is to stretch out the vowels according to how accommodating  the 
speaker is willing to be.
1. "This one you want to pay by installment, oso can."
2. "You only owe me $5. But if you want to give me $10 oooooso caaaan."

OW BWAY OOH KWEE
Hokkien phrase meaning, "There's a ghost behind you."  Often shouted when playing football or hantam bola, to warn someone that an opposing team member is behind them.

OWN TIME OWN TARGET/O.T.O.T. (contributed by Sliide)
Another Army-inherited term, meaning to perform a task at one's leisure, or using one's discretion.
1. Private: "Eh, Sergeant! Give how long to sio?" (Sergeant, how long is our cigarette break?"
    Sergeant: "O.T.O.T."
2. "This assignment is not very urgent. You own time own target can oreddy."