liquid
Explanation
The Joke
A TSA agent tells a traveler that no liquids are allowed on airplanes -- a reference to the real and widely mocked TSA rule limiting liquids in carry-on luggage. The traveler, however, is apparently some kind of liquid-based or partially liquid being, and takes deep offense, shouting "That's a slur!" He protests that he is "40% solid" and has "a mind and feelings just like you," treating the TSA's blanket ban on liquids as a form of bigotry against liquid-people.
The TSA robot (drawn as a boxy, mechanical figure) fires back with "Go back home and drink some water, water-bag!" -- turning the tables by using a slur against humans (who are, after all, mostly water by composition). This reframes the familiar airport security annoyance as an absurd civil rights conflict between solids and liquids.
The Humor
The comic works on multiple levels. On the surface, it takes the universally annoying TSA liquid rule and imagines a world where "liquid" is an identity category, making the policy sound like institutional discrimination. The escalation from bureaucratic inconvenience to full-blown slur-trading is fast and absurd. The robot TSA agent calling the human a "water-bag" is a particularly nice touch -- it is scientifically accurate (humans are roughly 60% water) and works as a callback to the idea that the line between "liquid" and "solid" beings is blurrier than anyone wants to admit.