Well the "black" community DL used to mean just keeping shit a secret but today it pretty much just means a bisexual man in the closet. Not just black people say it but it's just used by those down with urban(black) culture. Give it time and it may catch on with the masses in America like so much other black slang has. And on the side note the amount of DL brothas that hit me up online is truly mind boggling.