Answer: Actual scientific theory!
From Penny tirelessly working to book a solid acting gig to Amy trying to convince Sheldon to be intimate with her, The Big Bang Theory characters are overflowing with potential. Believe it or not, "The Mixed Potential Theory" is not the title for an episode where Penny tirelessly tries to book a solid acting gig or Amy tries to convince Sheldon to be more affectionate.
Instead, this actual theory is often used in electrochemistry, which is the study of the chemical processes that cause electrons to move. Sadly, any further explanation would require you to take a class about redox reactions and oxidizing agents.