Technical
Explanation
The Joke
A banner reads: "Life tip: It is technically correct, and weirdly unnerving, to refer to mathematical facts in the past tense." One character demonstrates by asking, "Did you know that 11 was a prime number?" The other person reacts with visible alarm: "I... AAAH!"
The Humor
Mathematical truths are considered timeless and eternal — 11 doesn't just happen to be prime right now, it is prime by definition, always and forever. By referring to 11's primality in the past tense ("was a prime number"), the speaker implies that this is no longer the case, which is logically impossible but instinctively terrifying. The listener's panicked reaction reflects the sudden, irrational fear that the foundations of mathematics have somehow changed.
The comic is "technically correct" because the past tense statement is not false — 11 was a prime number (and still is). But the pragmatic implication of using past tense in English is that the condition no longer holds, which is what creates the unease. This is a joke about the gap between logical truth and conversational implicature: the statement is literally true but communicates something deeply wrong.
Broader Context
SMBC regularly explores the humor in mathematical pedantry and the quirks of how language interacts with formal logic. The comic taps into a well-known philosophical idea — that mathematical truths exist outside of time — and finds comedy in the simple act of conjugating a verb incorrectly. It also plays on the popular internet culture concept of being "technically correct" as "the best kind of correct."