Title text: To compensate for this, I plan to spend 2013 doing nothing but talking about Mayans. My relationships with my friends and family may not fare well.
This comic is in reference to the fact that the Mayans, an ancient civilization in the Americas, created a calendar that ends (or, more accurately: restarts) on December 21, 2012. This date is regarded as the end-date of a 5,125-year-long cycle in the calendar used by the Mayan culture. Knowing this, some thought that the world was going to end on that date.
Consequently, a lot of people were talking about the Mayans, concerned that the world might end. After December 21, 2012 passed uneventfully, everyone was less concerned about the Mayans, because the world didn't end. It is worthy of note that this comic was published nearly a year before the "significant" date and that Randall predicted both the hype and the aftermath perfectly.
There is a measure of irony to be had in how the Mayans who still exist today were largely ignored by the doomsayers. "Or acknowledging that huge city-building ancient American civilizations existed at all."
In the final frame, Megan parodies the phrase, "Those who fail to learn from history are doomed to repeat it," applying a twist to suggest an academic context. In most American schools, a Grade Point Average is computed by assigning numeric value to each letter grade: A=4, B=3, C=2, D=1, and F=0; receiving high marks (all A's) thus yields a 4.0 GPA. However, if you "Fail to learn from History" — that is, get a failing grade, F, and had at least 3 other classes (not an unusual course load) — you would still get a 3.0 with A's in those other classes. She is making the callous — if roundabout — observation that failing to grasp history, while no doubt troubling, isn't an academic show-stopper (perhaps explaining why so many Americans are so bad at it). Her comment may also be taken to suggest that people who feared the Mayan "prediction" of the end of the world would come to pass had failed to appropriately extrapolate from the numerous other faulty predictions of the end of the world. In fact the Mayans never actually predicted the end of the world with their calendar, those who failed to learn from history jumped to conclusions yet again.
The title text jokes that to make up for the lack of Mayan discussion, Randall plans to spend 2013 talking solely about Mayans. For obvious reasons, people would probably get sick of this very quickly, hence his comment that his relationships might not fare well. Thankfully, as of 2014, not a single published xkcd comic of 2013 featured any Mayans, so we're pretty sure this promise wasn't kept.
- [Cueball and Megan are talking.]
- Cueball: Well, it's 2012.
- [This panel has no upper and lower borders.]
- Cueball: Yup.
- Megan: Only 354 days left until everybody abruptly stops talking about Mayans.
- Cueball: Or thinking about Mayans.
- Cueball: Or acknowledging that huge city-building ancient American civilizations existed at all.
- Megan: You know what they say — those who fail to learn from history can still manage a 3.0 if they ace their other subjects.