Number Hunt
Explanation
The Joke
In a dystopian setting, an authority figure (resembling a robot or armored enforcer) announces that all remaining mathematicians will be eliminated before they can "contaminate our kids with their number stuff." A bystander asks how they plan to selectively detect mathematicians. The enforcer has a simple test: it states a mathematical fact -- "Did you know that every even number greater than 2 can be expressed as the sum of two primes?" -- which is a statement of Goldbach's Conjecture, one of the oldest unsolved problems in mathematics.
A nearby person involuntarily reacts with a snort or laugh (the "SNRK" reaction), revealing themselves as a mathematician who recognizes the subtlety -- Goldbach's Conjecture has never actually been proven, so stating it as a known fact is technically incorrect. The enforcers then open fire, having successfully identified a mathematician by their inability to let an unproven conjecture be stated as fact.
The Humor
The joke works on multiple levels. First, it parodies anti-intellectual purges by imagining one directed at mathematicians specifically. Second, the "trap" is brilliantly designed: only someone with mathematical knowledge would react to Goldbach's Conjecture being stated as proven fact, because to a layperson it sounds like a perfectly reasonable trivia tidbit. The mathematician's compulsive need to correct the record -- reacting involuntarily to an unproven conjecture stated as fact -- is a loving jab at how mathematicians are constitutionally incapable of letting imprecise mathematical statements slide.
References
Goldbach's Conjecture, proposed by Christian Goldbach in 1742, states that every even integer greater than 2 can be expressed as the sum of two prime numbers. Despite being verified computationally for extremely large numbers, it remains unproven as of today and is one of the oldest open problems in number theory.