Pareto
Explanation
The Joke
A man is sitting on his couch and announces, "I've done it. I've reached total Pareto optimality in my life, and no change can conceivably be made that wouldn't make things no worse." In economics, Pareto optimality (or Pareto efficiency) is a state where no reallocation can make any one person better off without making someone else worse off. The man has applied this concept to his own life, claiming he has achieved a perfect equilibrium.
In the next panel, someone peeks in from behind a wall and suggests: "Basically it just means 'the couch methodology' -- for a week, drinking cheap vodka and watching cartoons, and I would either be better off or the same." The final panel caption reads: "True, it is wonderful." The joke is that the man has reframed total laziness and inaction as a form of optimal efficiency.
The Humor
The humor comes from the absurd misapplication of a serious economic concept to justify doing absolutely nothing. Pareto optimality is normally discussed in the context of resource allocation across a society or market. By applying it to his personal life, the man has found an intellectually sophisticated-sounding way to argue that sitting on the couch drinking vodka and watching cartoons is the rational, optimal choice. The comic satirizes both the tendency to use academic jargon to rationalize lazy behavior and the way economic concepts can sound profound while describing something trivially obvious. It also pokes fun at a certain type of person who uses knowledge of economics or game theory to construct elaborate justifications for doing whatever they were going to do anyway.
References
Pareto optimality is named after Italian economist Vilfredo Pareto (1848-1923). A Pareto optimal state is one in which no individual can be made better off without making at least one other individual worse off. It is a foundational concept in welfare economics and game theory.