Best definition
whiny prick
noun: One who is low enough to gripe and spread hate and offensive things, targeting tumblr users in particular, likely

because he/she/ze is either dissatisfied with his-/her-/zir- self or is envious of the positivity and support for one another found within tumblr fandoms. These creature have recently been seen roaming the fandom tags of the tumblrsphere, taking out their own frustration on innocents. They seem to have originated from certain 4Chan boards. If encountered, the best response to a “whiny prick” is to merely cross yourself (if you do that sort of thing), report them, and pity the fool who has such a lack of basic human decency as to assault our fellow fans and friends.

Tumblr has recently experienced an infestation of whiny pricks, who are envious of the fandoms and seek to eradicate all happiness.