Al escucharlas yo no les entiendo nada, solo cuando las leo puedo entender un poco, pero ni siquiera un 20% de lo que pretenden decir.
Aquí se muestra en un artículo de lo que logró un estudiante al tratar de traducir la canción de un rapero conocido.

Lyrics:
First things first, I poppa, freaks all the honeys
Dummies - playboy bunnies, those wantin’ money
Those the ones I like ‘cause they don’t get nathan’
But penetration, unless it smells like sanitation
Garbage, I turn like doorknobs
Heart throb, never, black and ugly as ever
However, I stay coochied down to the socks
Rings and watch filled with rocks

TRANSLATION:
As a general rule, I perform deviant sexual acts with women of all kinds, including but not limited to those with limited intellect, nude magazine models, and prostitutes. I particularly enjoy sexual encounters with the latter group as they are generally disappointed in the fact that they only receive penile intercourse and nothing more, unless of course, they douche on a consistent basis. Although I am extremely unattractive, I am able to engage in these types of sexual acts with some regularity. Perhaps my sexuality is somehow related to my fancy and expensive jewelry.

Lyrics:
And my jam knock in the Mitsubishi
Girls pee pee when they see me, Nava-hoes creep me in they tee pee
As I lay down laws like I lay carpet
Stop it - if you think your gonna make a profit

TRANSLATION:

I enjoy playing my music loudly on my car stereo. Apparently, women enjoy this also because they become sexually aroused when they see me driving. Oddly enough, when I visit the Native American reservations, some of the more sexually promiscuous Indian women attempt to seduce me in their homes. Their intent is to divest me of my earnings. Such actions are unacceptable.

RAP LYRICS TRANSLATED