Category:Banned from conferences
These comics refer (either in the comic itself or in the title text) to the protagonist (Randall) being banned or thrown out from conferences or specific fields of study.
Especially in the second-to-last comic to use this, 541: TED Talk, there is a whole list of conferences from which he has been banned. This has sometimes resulted in him being invited to those conferences, see more here on this PyCon response to Randall claiming he was banned from their conference.
See also 451: Impostor.