The DL

The DL or The Down Low, like many terms and phrases in the American culture, can attribute their genesis to the Gay and Urban Black community, The, "DL" has evolved to be used universally to refer to activities conducted secretly and behind the scenes. The DL can also refer to behavior described as slick or deceptive.
The term has truly evolved. In recent times DL has gone from being used exclusively to describe covert male homosexual behavior of a man fronting (portraying himself), as a heterosexual but in reality is actually a closet Gay man, to now refer to any behavior, action, or behavior that can be described as secretive or deceptive.

Etymology
DL or “Down Low”, attributes its genesis from the Inner City Black and Sub Culture. The Black community was slow to accept the male homosexual in their community so Black Men were maintaining a cover, by acting as they were only into the Ladies. Their homosexuality was secret and thus adopted the term, “Down Low” to refer to a man that is a closet homosexual or a man that engages in sexual relations with both male and female partners. The term evolved to identify such men as their female partners were discovering that their Man was subversively engaging in sexual relations with another man on the side, (on the DL) while their female partner was unaware of his behavior and sexual preference. Prior to the Homosexual descriptive, the term was used to describe: any kind of secretive, slick, and/or deceptive behavior.

Men, usually black or latino, who partake in heterosexual relationships, but also engage in homosexual activities with other men at "oppurtune" times. These homosexual encouters happen purely for sex not a relationship or emotional connection. Over 73% of black males, as reported on Oprah, are on The DL.

DL
DL means Down Low. This is basically a man who is seen publicly as straight, identifies and ‘acts’ straight; but secretly is attracted to or has sex with other men.

A "Straight" Man That Usually Has A Girlfriend Or Wife But, He Also Has A BoyFriend On The Dl (Down Low). Most Dl's Aren't Gay Just Bisexual But, Afraid To Come Out Because Of Family Or Friends.

DOWN LOW see also D low--Hidden, concealed,secret.Specifically used to refer to covert male homosexual activity.Whether we're talking about guys who freak with their boys, or hustlers who are strictly "gay for pay" Thanks to homophobia, bigotry and all that bullshit in their communities they prefer to keep things quiet: On the DL.

Abbreviated for "Down Low." Sometimes used to say that you are still in the closet. Someone that is afraid to let the world know that they have sex with their homeboys.

short for on the down low. meaning a brotha is secretly looking for have sex with another dude