It's part of a metaphor S&A picked it up from Johnathan Haidt (pronounced like height, not hate), He introduces it in his book The Happiness Hypothesis, but he brings up the metaphor in probably half of his recorded lectures and seminars. I believe it originates in Hindu teachings.
The metaphor is that a person can be conceptualized as an emotional elephant and a rational human rider. The elephant is in control, but the rider can try to steer the elephant. The more rational a person is, the more their rider is in control, but even a rational person can lose control if the elephant encounters something that triggers it.
In the S&A community, Adam is described as an elephant being ridden by a smaller elephant, due to past interactions like he had with Max.
Somehow he even manages to interrupt people when there's a script.
Also, here's the book she's reading for the real pervs. I think I actually read it before, which I wasn't expecting.