FTLY is an acronym standing for Fuck The Lumber Yard.
The lumber yard signifies a place where people work, thus, if you are going out drinking for example and you are you going to skip work the next day you scream out FTLY. Which means you do not care for work the next day because of your plans tonight (usually including alcohol) are of a far larger significance.

A man who messes around with other men, but no one would ever know by looking or talking to him. Used by gay black men to identify masculine gay men or DL Brothas.