I do enjoy a good visual gag, and an old favorite of mine is “there is Math on a Board in the background that contextually makes no sense.” This broadly comes in 3 flavors I enjoy:
• the board is in front of a classroom, and the Math is waaay too advanced for whatever level of pupil these kids are supposed to be; like having the calculus integral in front of kindergartners, or relativistic physics in front of high schoolers.
• the board is in front of Criminals, who are Planning Something, and by all rights there ought to be no Math there to begin with. Like. You’re planning a Heist why do you have the Full Lagrangian on there. Are we taking a rocket to the bank.
• the characters are super-genius science fiction people. The Math is “Pi≈3.24” with an unlabeled pie chart.