> If two people disagree on whether something is funny, who's wrong? You can't say either of them is. There's no reward function for funny.

Laughter is the reward. N of 2 is a small sample size, but if one person laughed you could say it was 50% funny.

> a really good joke is recent, relevant, and shows deep understanding of its subject

These can help, but it ultimately doesn't matter how recent, relevant, or deep a joke is. If no one laughs, it wasn't funny.