This document outlines 12 common types of social media "monkeys" or personas based on their understanding and use of key performance indicators like Return on Investment (ROI). It describes personas like the "RETURN ON Incompetent" who uses fuzzy math, the "RETURN ON Impressions" obsessed with vanity metrics like followers, and the "RETURN ON Incalculable" who rejects ROI metrics altogether. The document emphasizes that ROI should focus on the relationship between gains from an investment and the costs of that investment, using the same currency to measure both.