B = Бочка(kick drum)
PF = Обычный снэр(classic outward snare)

(B)if your m-PF-other B-B-on-B-PF-ly knew B-knew PF B-B -- B PF

(B)if your m-PF-other B-B-on-B-PF-ly knew B-knew PF
That B-you B pff-been try(B)ing to B-get B-(Pff)with me B-pff-B-B--B-pff

Непосредственно сам текст песни!

(вдох,выдох и вдох как на 6 секунде IYMOK)
If your mother only knew (битуеш)
If your mother only knew (битуеш)
If your mother only knew
That you was tryin to get with me (битуеш)
If your mother only knew (битуеш)
If your mother only knew
She'd probably throw (битуеш)
You out her home (beatboxes)
You'd probably be upon a park bench all alone (битуеш)
If your mother only knew (beatboxes)

This is the tricky part
The beat, and the chorus, at the same time
(битуеш)
if your mother only knew
If your mother only knew
If your mother only knew
(битуеш)
if your mother only knew

Ya'll don't think I'm doin' that poopoo?
Ya'll don't think I'm doin' that poopoo?
You think it's some other poopoo going on?
I'm gonna slow it down
I'm gonna slow it down a little bit so y'all can hear the
pronunciation on everything I'm saying
Check it out

(Медленный бит) If your mother only knew
(beatboxes)
(while beatboxing)if your mother only knew
(Медленный бит)

И пару ссылок на туториалы :
1) If Your Mother Only Knew Beatbox Tutorial
2) IYMOK Beatbox Tutorial Supplement