A red piller is someone who believes that women are actually the privileged group instead of men. The argument goes: although women don't inhabit the highest echelons of power, the vast majority of men don't, either. For the most part, women have it better. People hold doors for them. They get less severe sentences (and charged less) in court. A woman can get men to give them free things at a club, whereas, if a man asked for the same from a woman, he'd be told to fuck off. Women have large and efficient support groups while men don't.

It's called redpilling because of the scene in "The Matrix" in which Morpheus offers Neo the red pill or blue pill. Only the red pill will show him the uncomfortable truth. Red pillers see themselves as having been awakened to the uncomfortable truth that women have it better than men.

Their teachings can be found at the subreddit "theRedPill", which talks about, among other things, how to be a pickup artist and how to beat a woman and get away with it.

A term used to reference cannabis/marijuana/weed.

A red piller is someone who is proficient (or at least thinks that they are) in the act of redpilling. In most cases, the red piller is politically motivated and attempts to lead their target to their side of the political spectrum through a variety of mediums- most commonly memes, (edgy) jokes, and (mis)quotes.

While there are examples of red pillers all over the political spectrum, they are most prevalent on the far left and right, along with fringe groups of fascists, communists, or anarchists -recently being used nearly exclusively by the right wing.

The "red pill" term comes from The Matrix, in which a character chose between a blue pill and a red pill, where the blue pill would let them live freely and without knowledge of the inner workings of their world, and the red pill would allow them to "wake up" from their ignorance, and learn the "truth."