Looking at the concept, and especially articles written by large, MSNBC-owned companies (This is where the ad revenue you generate goes to), it almost certainly plays on the social and penis size dynamics, which has been a topic used to ridicule people. Turning this into a joke format almost always entails that if someone behaves in a way desirable to you, you reward them with a favoured social label (“Big Dick Energy” in this case). The entire system runs on subjective belief on what a good person is, and the label has mostly been used by leftists on social media platforms such as Twitter, typically feminist women. (Who also tend to be “jokingly” judgmental in other ways, such as Zodiac signs) That is only my analysis on this new “fad” of going around saying people you like have “Big Dick Energy”.