I don't think you had this meaning in mind.
"On the down-low, or on the DL, refers to information that's kept quiet or under wraps. It emerges in Black slang by the 1990s. Both down and low underscore the slang's sense of “quiet” and “hushed.” Since at least the early 2000s, down-low refers to men who secretly have sex (on the down low) with other men. " from google.
I wish I had not caught up on this thread tonight. Now I know something I really wish I did not know.
Sure gives new meaning to that old pop song...
"So I creep, yeah
Just keep it on the down low
Cause nobody is supposed to know
So I creep, yeah
Cause he doesn't know what I do
And no affection goes to show"
I bet 40 years from now teenagers will be pointing to this song and saying, "See? Even back then they were talking about gay sex."
Where is the facepalm emoji when we need it?