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1.
FDL
The FDL is an extention of the DL or down low, the fdl meaning f*cking Down low. Usually used to express that the fact just disclosed should never be shared
jim: Ohh your gonna propose to Mary tomarrow? Ok ill keep it on the DL.

joe: no Jim, you better keep it on the FDL.
by <blank><blank> January 08, 2009