Unfan

[Monty]

The act of becoming a fan of an entity on Facebook in order to publicly [criticise] said entity (verb), or a person who does this (noun), as exemplified by the mass criticism on Nestlés Facebook page over the companys use of [palm oil] and subsequent censoring of its online presences.
Has parallel behaviours in other social media (though the irony doesnt translate as well in more language-neutral cases like [Twitters] follow function).