down low

Noun

 * 1) A state of secrecy.
 * 2)  The state of being a man who secretly sleeps with people other than his partner.
 * 3)  The state of being a man who secretly sleeps with other men.
 * 4)  A man who secretly sleeps with other men.
 * 1)  A man who secretly sleeps with other men.
 * 1)  A man who secretly sleeps with other men.

Usage notes

 * In all senses except the last, always preceded by on the.

Adjective

 * 1)  Undercover or lying about one's identity.
 * 2)  Purporting to be heterosexual while engaged in sex with men.