143= (text message) A numerical representation of the expression 'I love you' where each of the three numbers represents the amount of letters in each of the words. Some lovers often text each other 143, especially on the mobile phone, just to remind the other person that they love them.

I'M A ONE-BIKE KIND OF GUY= I'm a person who only likes to have one bike.
This sentence sounds a bit stupid, since most people only have one bike (even rich boys like here), but this is echoing a much more usual sentence: "I'm a one-woman kind of guy", which means I'm a faithful lover and when I love a woman I never think of any other. So this sentence is preparing us to think that the song is about one true love.

NEW FLAVOUR OF THE WEEK?= A new girlfriend? (implying that he changes girlfriends frequently).

YOU DON'T EVEN KNOW= She's more fantastic than you can imagine.

MAN= (coll. AmE) A cool way to address a male.
- Hi man, how you doin'?
- Not much man, how 'bout you?
- Listen man, look at this.
- Oh man, that's cool, where did you get it?

WHO IS IT, THOUGH?= This THOUGH at the end of the sentence is used in colloquial English as an equivalent to ANYWAY.

YA= (coll.) /jə/ (usually sounds /jʌ/ at the end of a sentence) A relaxed pronunciation for YOUR, for YOU'RE or for YOU (you can find it in more places here in the lyrics).

SHORTY= (coll. esp. AmE) A very cute girl (usually spelled SHAWTY in American English, because in America the R is pronounced, so SHORTY would sound different there except for many black people who don't pronounce the R).

WHO DAT YOU THINK ALWAYS MISSING YOU= A very ungrammatical sentence that probably means "who do you think is always missing you?" (a rhetorical question, it really means: "I'm always missing you"). DAT is black American English for THAT.

I CANNOT GET ENOUGH OF KISSING YOU= I always want to kiss you and never get tired of that.

I SHED A TEAR OR TWO= I cry a little bit. The phrase ONE OR TWO means simply "a few" and to shed a tear is to cry.

ON THE GRIND= (coll.) working hard.

AIN'T NO FORGETTING YOU= It's impossible to forget you. The word AIN'T is colloquial English for the negative of the verb "to be" or "have" in the present. Here, AIN'T means THERE ISN'T, which makes this sentence a double negative because then he uses NO. Double negatives are common in colloquial speech but incorrect in standard English.
I ain't French = I'm not French
He ain't got no money = He hasn't got any money
Ain't you seen 'em? = Haven't you seen them?

COZ= (coll. also spelt CAUSE or CUZ in AmE)

IYIYI= /aɪjaɪjaɪjaɪ/ A very exotic name for a girl, only that it is not a name, it's only a strange spelling of "I-I-I-I", the repetition of the first person pronoun (I) and it's simply building up for the last sentence of the chorus: I-I-I'm missing you, missing you. That strange spelling is probably one of the most important assets of this song, it quickly catches your eye, your imagination and your curiosity, so people notice the song better, but if you look at it carefully, that invented spelling doesn't even fit the sound of it (not that it needs to either), it's got one I or Y too many. The other strange thing in the title of the song is the wrong succession of capital and small letters (iYiYi), instead of using a capital letter for the first one (Iyiyi) and which makes it look more like a pattern than like a word; that also adds to the weirdness of the title and captures your attention at once. Many people think Iyiyi is a girl's name from some exotic distant island maybe, and I wouldn't be surprised to find that some people are giving that name to their newborn baby girl even as we're talking (poor thing!). In fact, some people on the Net are already using that as a first or middle name and now you find people virtually called "Nancy Iyiyi" and things like that. Oh, well.

MISSING YOU= If you miss a person, you are not with them but you would like to be with them.

I'MA= (coll. esp. AmE) I'm going to = I'm gonna. This future form is very colloquial but now it's often heard in songs even in British English. You can also find other spellings for this: I'mma, Ima, Im'a, I'm a, I ma'.

I'MA TEXT YOU UP= I'm going to send you a text message to your mobile phone.

WHENEVER= Every time, always.

I'M WISHING I WAS BACK HOME= Notice how we use the past tense after the verb WISH:
- I wish it rained = I want it to rain (but it probably won't)
- She wishes he loved her = She wants him to love her (but it's not easy)
We use the "unreal past" because it's not a real thing, only something we wish, but it's not true. So we're not talking about the past, we're talking about something unreal. (if you have the subjunctive tense in your language you can easily understand this, because the unreal past is the equivalent to the past subjunctive in many languages like Spanish, French or Italian). The unreal past is also used in other unreal or hypothetical situations like in second type conditionals:
- If you were rich you would live in a palace (but you don't, because you are not rich).

WHEN WE'RE APART= When we are separated from each other, when we are not together.

I'M ON MY WAY= I'm coming to you.

TRUST EVERY WORD I SAY= Believe everything I say.

I CAN'T WAIT TO SEE YOUR FACE= I really want to see you again, I'm so impatient.
- So tomorrow you're travelling to Egypt.
- Oh yea, I can't wait!

I'LL BE RIGHT BACK= I'll come back really soon.

GOTTA= (coll.) Have got to, must.
- I gotta go = I have to go / I've got to go / I must go.

I MEAN WHAT I SAY TO YOU= My words are true, I'm not lying.
If you mean something, you are telling the truth.

WE WERE THE PERFECT MATCH= We are perfect for each other. A match is two things that fit together, that go perfectly well together. In love, your match is your true love, the person who is perfect for you.

A GIFT= A present.

SENT FROM ABOVE= Sent from heaven, sent by God.

TEXT= This word, used as a verb, means to send a text message on the phone.

1-4-3= As we explained at the beginning, this means "I love you".

LET YOUR HEART TAKE THE LEAD= Act according to what you feel, not to what you think.

LIL MAMA= (coll. AmE) Little mama = Shorty, cutie. You say this to a girl you find very cute and sexy, a very attractive woman.

AIN'T NOBODY ELSE= There is no other person. This sentence has a double negative (see comments when we explained AIN'T above).

I GOT INTENTIONS JUST TO PLEASE YOU= I only want to please you, to do what you like.

SUPERFLY= Very very fly. The word FLY as an adjective is colloquial American English for a person who is very cool and sexy.

YOU MORE PRECIOUS THAN A PEARL= You are very valuable, you are really fantastic.

HIT THE FAN= (expression) To become publicly known.

I DON'T WANNA ROCK WITH A BRAND NEW BAND= I'm not interested in getting famous playing with a completely new band.

GRAND= Awesome, amazing, spectacular, really important.

I'VE BEEN ALL OVER THE LAND= I've travelled to many places, many countries.