Fun Fact
Explanation
This comic presents what appears to be a factual educational statement at the top: "Fun fact: anything that is true of humans is also true of humans with a given profession." Below, one woman says to another: "Did you know that you can make cheese from clown milk?"
The joke works by applying the stated logical principle in a disturbing way. The "fun fact" header establishes that any property of humans in general also applies to humans who happen to have a specific job. Since humans are mammals that produce milk from which cheese can theoretically be made, this is technically also true of humans who are clowns. Therefore, "clown milk" and "clown cheese" are technically real concepts.
The humor comes from the visceral discomfort of combining the mundane biological fact (humans produce milk) with a specific profession (clown) to create something that sounds deeply unsettling -- "clown milk" and "clown cheese." The comic satirizes how technically correct logical statements can produce conclusions that feel profoundly wrong, and how adding a profession to a normal human attribute can make it sound bizarre or horrifying.