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1.
Noun:
One who participates in the daily viral spread of a Facebook survey, app, game, chain letter, or similar device but does not actually initiate the spread of it nor is creative enough to do so. A Facebook lemming only mimics the activities of other Facebook users.

Origin:
Macrodot circa 02/02/2010
"Im tired of getting Farmville updates from Susan. She is such a Facebook lemming!"
by macrodot February 02, 2010