“Take the blue pill and the story ends,” Morpheus tells Neo. “Take the red pill and you stay in Wonderland and I’ll show you how deep the rabbit hole goes.”
An influence on the blue and red pills of The Matrix could have been Douglas R. Hofstadter’s 1979 book, Gödel, Escher, Bach: An eternal golden braid, in which a turtle and the philosopher Aristotle drink jars of blue liquid and red to “explode.” “Inside and outside MC Escher labyrinth drawings. Drinking the jars, like taking the pills in The Matrix, reminds Alice of drinking a bottle labeled “DRINK” and eating a cake labeled “Eat Me,” which causes it to contract and grow, respectively.
In the language of the Matrix, the redpills are those who know the structure of the Matrix, while the bluepills do not.