QAnon or simply Q is a conspiracy theory group who believe that there is a secret cabal of Satan-worshipping, pedophilic cannibals based in Hollywood that must be stopped. The group is led by Bob White. They are the main antagonists of the Season Twenty-Four episode, "South ParQ Vaccination Special".
According to QAnon, the cult is comprised of political and Hollywood elites. They allegedly abduct children and harvest adrenochrome from their blood for a euphoric and life-enhancing benefit. Alleged members include Barack Obama, Oprah Winfrey, and Joe Biden. QAnon believes that the cult puts mind control chips in the COVID-19 vaccines, hence they try to stop people from getting vaccinated. In order to spread their beliefs, QAnon set up a home tutoring service, Tutornon. Tutors brainwash children into believing what they believe. These children form the children's arm of QAnon, Lil' Qties.
QAnon considers Herbert Garrison to be "The Chosen One". They erroneously interpret what he says is some kind of signal. For example, when Garrison tells Bob White to "get a fucking life" and "blow shit out your dickhole", Bob interprets this to mean that QAnon has to get their message out to children.
It is implied that QAnon's theory is indeed correct in South Park. When Bob White tries to put a stop to the alleged cult, he gets controlled by them; the show gets edited digitally and he is turned into a giant penis.