This is getting to be fun.

I searched for the definition of 'pickney,' and it's Jamaican for child.

I guess a mango walk is place where mangoes grow. Here's the first verse of another song:

My brother did-a tell me that you go mango walk,
You go mango walk, you go mango walk,
My brother did-a tell me that you go mango walk
And steal all the number 'leven.

(I bet the number 11's are the best kind.)

Here's my translation thus far:

Mumma, mumma, dem ketch puppa,
Dem ketch 'im dung a mango walk.
If a neva run dem woulda ketch mi tu,
So mi sing sweet song an' play guitar.

Mama, Mama, they caught Papa,
caught him down at the mango orchard.
If I hadn't run, they would have caught me too.
So I'll sing a sweet song and play guitar.
(chorus)
Wai oh, Mattie rag,
Wai oh, Mattie rag.

2. Puppa go down a mango walk
Cause 'im ear wan hog a chaw a piece a rag.
Wen 'im ax 'im a chaw fa rag,
'Im tell 'im sey a Mattie rag.


Papa went down to the mango walk
because ? chew a piece of rag (is rag chewing tobacco?)
When he (Papa) asked him (another male) for a chew of rag
he told him Papa, "Say a Mattie rag."
(Chorus)


[Now the speaker is the singer's mother:]

3. Pickney hear whe yu mumma sey,
Yu betta 'tap go mango walk.
If yu neva run dem woulda ketch yu tu,
So sing sweet song an' play guitar

Child, hear what your mother says.
You better stop going to the mango walk.
If you hadn't run, they would have caught you.
So sing a sweet song and play guitar.