It's a memorable quote in the bible found in Genesis 4:9, meaning:

1. Are you responsible for how you respond to your brother?

2. Are you held accountable for how you treat your fellow man?

It's really a sarcastic question/remark from Cain to God after Cain killed his brother, Abel, to keep from admitting to the fact that he did kill Abel.
Nino Brown: To CMB. On and on. Am I my brother's keeper?

CMB: Yes I am.

Nino Brown (louder): Am I my brother's keeper?!

CMB (louder): Yes I am.!

Nino Brown (louder): Am brother's keeper?!!!

CMB (louder):!!!

The Duh Duh Man (studdering): Yes.......I am.!!!

-from NEW JACK CITY (1991)
by Mr. Terrence L. Trezvant March 23, 2006
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