2012-06-09
Explanation
A young man asks a priest why the Church opposes Dungeons and Dragons, pointing out that it's all pretend and there's no chance of players actually becoming murderers or witches. The priest agrees -- that would be crazy, and the Church doesn't oppose D&D for those reasons. When asked "Then why?", the priest pulls out a Venn diagram showing "Forms of Birth Control" as a large circle with "D&D" as a subset entirely contained within it.
The joke plays on the well-known stereotype that tabletop RPG enthusiasts (particularly D&D players) are socially awkward and unlikely to have romantic or sexual relationships. By classifying D&D as a "form of birth control," the priest is saying the Church opposes it not because of any occult danger but because it is so effective at preventing its players from reproducing. This works on multiple levels: it subverts the expectation that the punchline will involve the historical "Satanic Panic" moral panic of the 1980s (when some religious groups genuinely believed D&D promoted witchcraft and devil worship), and instead delivers a completely different kind of insult. The Venn diagram showing D&D as a proper subset of birth control methods is an extra mathematical touch typical of SMBC's nerdy humor -- it implies D&D is technically a form of birth control, just a very specific one that works through social rather than biological mechanisms.