The term "pure vanilla" is an investment strategy that involves holding only U.S Treasury bonds, which are considered one of the safest and most liquid assets in the world. This type of portfolio consists solely of government debt securities, providing a stable return with minimal risk. The phrase "pure vanilla" is often used to describe this simple and straightforward approach to investing, as it relies on the safety and reliability of U.S Treasury bonds for consistent returns without taking on additional risks or complex strategies.