Title text: Hey, what are the odds -- five Ayn Rand fans on the same train! Must be going to a convention.
"Sheeple" refers to people as sheep, who blindly follow direction without thinking for themselves. The phrase "Wake up Sheeple!" has been used in xkcd other times. In this comic, each person on the train considers themself to be an individual mind, and everyone around them as "sheeple." Ironically, although each of them thinks about how individual they are, they are all collectively thinking exactly the same thing. The comic can also be taken as a warning to not assume that you have more consciousness than someone else, since for all you know they could think the same about you.
Ayn Rand was a Russian-born American novelist and activist whose most famous books include, Atlas Shrugged, Anthem and The Fountainhead. She was philosophical pro-individual and anti-collectivism. Sheeple coordinates with Ayn Rand's novel, Anthem, set in the distant future in which the word "I" has been abolished and the "evils" of the communal values have created a new dark age.
A possible further irony can be found in the tile text. Rand enthusiasts would seek individualism and independence from social pressures; however, a convention could be interpreted as a social collective of people who have similar interests in a subject. These ideas would seem to be opposites of each other.
- [A thought bubble is shared between the five occupants of a subway car.]
- All: Look at these people. Glassy-eyed automatons going about their daily lives, never stopping to look around and think! I'm the only conscious human in a world of sheep.