Thaler's Mug
 THE BEHAVIOURAL CONCEPT
The endowment effect.
It's the idea that "people often demand much more to give up an object than they would be willing to pay to acquire it" - so in the original Thaler experiment, people who were endowed with a mug felt it was worth more solely because it was theirs. Crazy right? 
So, has any Thalers in your life convinced you to buy a ridiculously expensive mug lately?
 THE inspiration
Thaler's research on the endowment effect using mugs. So naturally, the comic had to be drawn on a mug!! 
Cool concept + Creative Object = Crazy Comic 
The OG paper, if you haven't read it, everything will make sense after you do: 
Kahneman, D., Knetsch, J. L., & Thaler, R. H. (1991). Anomalies: The endowment effect, loss aversion, and status quo bias. Journal of Economic perspectives, 5(1), 193-206.