Someone who is completely addicted to Facebook, but tries to claim they really aren't when mocked about their addiction. They claim they "rarely use" Facebook. Like a crackhead, they just want to log into Facebook "one last time".

The FB denier is usually an adult, as at least teeny boppers have the decency to flat out admit they are addicted.
Jr (a prototypical Facebook denier): I rarely use Facebook.

Kip: Yo brutha, see that My Little Pony group on FB??

Jr: No. Sweet! Add me, bro!
by moraleboatanchor April 14, 2013
Get the Facebook denier mug.