What does it mean to be on the down low?

Answer by  lingo22 (13)

In its primary meaning (usually applied in the black community), a guy on the down low was mostly heterosexual (maybe even married) but having some secret homosexual experiences on the side. Now doing something on the down low is sometimes used just to mean "secretly", "on the QT", in general.

Answer by  grl1061 (86)

Being on the down low means that something is being kept quiet or "hush hush". "Keep it on the down low" is a frequent usage of the term.