i39m-not-going-to-seduce-you
Explanation
The Joke
The comic is titled "How to Get an Economist to Sleep with You." A woman approaches a man (the economist) and says, "Hi there. I'm not going to try to seduce you." When the economist asks "Why not," she explains: "According to the efficient market hypothesis, you're already taken."
The Humor
The joke hinges on a clever (mis)application of the Efficient Market Hypothesis (EMH) from economics. The EMH states that asset prices fully reflect all available information, meaning you cannot consistently find "undervalued" assets because the market has already priced everything correctly. Applied to dating, the woman is saying that if the economist were truly desirable (a good "asset"), he would already be in a relationship ("already taken") because the dating "market" would have already snapped him up. The humor comes from the economist being seduced precisely BY the economic reasoning -- the woman is speaking his language. It is a pickup line disguised as an insult, and the implication is that the economist finds the application of market theory so intellectually attractive that it works as seduction despite its content being unflattering.
References
The Efficient Market Hypothesis was developed primarily by economist Eugene Fama in the 1960s. It is one of the foundational concepts in financial economics. The joke also riffs on the common observation that economists tend to see everything through the lens of market dynamics, including personal relationships.