Pica is the name of an eating disorder where people eat non-nutritional items. An example is people with iron deficiency eating ice cubes; there is no iron in ice cubes, but iron and crunchiness sort of go together. By analogy, pica is also when people are missing something, and respond by doing something which doesn’t provide it, or doesn’t provide much of it, like watching sitcoms because they’re lonely or playing Minecraft because they feel unproductive.
AllAmericanBreakfast suggests that pica is like Goodhart’s Law, with the added failure that the metric being maximized isn’t even clearly related to the problem you’re trying to solve, giving two examples:
Evaluate your startup by the sheer effort you’re putting in? That’s Goodhart’s Law. Evaluate it by how cool the office looks? That’s pica.
Evaluate your relationship by the sheer amount of physical affection? That’s Goodhart’s Law. Evaluate it by how much misery you put each other through “for love?” That’s pica