Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This comic satirizes a common anti-gay argument found on the internet. A blogger (depicted as a stereotypical basement-dwelling internet commenter) writes that you "can't believe in evolution AND believe homosexuality is genetic," reasoning that "gay genes" shouldn't persist because "all human beings ever born are optimized for heterosexual procreation."

The middle panel pulls back to show the silhouette of the blogger at his computer, creating a dramatic pause. The final panel delivers the punchline: the same blogger writes "Anyway, my RPG just finished downloading. No more blogs for two weeks. Mom, if you're reading this, STAY OUT OF MY ROOM." The joke is the sharp irony that this person confidently claiming all humans are "optimized for heterosexual procreation" is himself clearly not reproducing or pursuing romantic relationships at all. The comic highlights the hypocrisy of someone who is, by his own evolutionary fitness standard, a poor example of "optimization" lecturing others about what evolution should produce.