The Wish
Explanation
The Joke
A genie offers a wish. The person wishes for world peace. The genie explains all the ways this could go wrong depending on interpretation: does "peace" mean the absence of violence (could be achieved by eliminating all humans), the absence of conflict (requires removing free will), or just the absence of war (still allows structural violence, poverty, and oppression)?
The person asks for a sandwich instead.
The Humor
The comic is fundamentally about the difficulty of specifying complex values precisely — a problem known in AI safety as the "alignment problem." "World peace" sounds unambiguous until you try to define it rigorously enough for a literal-minded genie (or a literal-minded AI) to implement.
The retreat to a sandwich is both funny and wise: simple, concrete wishes are less likely to go catastrophically wrong than ambitious, abstract ones.
Context
AI alignment researchers use genie/wish scenarios as intuition pumps for the difficulty of specifying human values. Stuart Russell's Human Compatible discusses this problem extensively. The comic is a compact, humorous version of a very real concern in AI safety research.