As it turns out, McGraw does think that it’s a new set of circumstances that violates the norm, as you guessed.http://leeds-faculty.colorado.edu/mcgrawp/Benign_Violation_Theory.html. It’s an evolutionary adaptation, as you imply.
Benign Violation Theory
The Humor Research Lab uses the Benign Violation Theory as its theoretical foundation.
In collaboration with Caleb Warren, McGraw has been developing and testing a general theory of humor called the benign violation theory. The theory builds on work by a linguist, Tom Veatch, and integrates existing humor theories to propose that humor occurs when and only when three conditions are satisfied: (1) a situation is a violation, (2) the situation is benign, and (3) both perceptions occur simultaneously. For example, play fighting and tickling, which produce laughter in humans (and other primates), are benign violations because they are physically threatening but harmless attacks.
A strength of the theory is that it also explains when things are not funny: a situation can fail to be funny because it depicts a violation that does not simultaneously seem benign, or because it depicts a benign situation that has no violation. For example, play fighting and tickling cease to elicit laughter either when the attack stops (strictly benign) or becomes too aggressive (malign violation). Jokes similarly fail to be funny when either they are too tame or too risqué.
According to the theory, a violation refers to anything that threatens one’s beliefs about how the world should be. That is, something seems threatening, unsettling, or wrong. From an evolutionary perspective, humorous violations likely originated as threats to physical well-being (e.g., the attacks that make up tickling, play fighting), but expanded to include threats to psychological well-being (e.g., insults, sarcasm), including behaviors that break social norms (e.g., strange behaviors, flatulence), cultural norms (e.g., unusual accents, most scenes from the movie Borat), linguistic norms (e.g., puns, malapropisms), logic norms (e.g., absurdities, non-sequiturs), and moral norms (e.g., disrespectful behavior, bestiality).
However, most things that are violations do not make people laugh. For a violation to produce humor it also needs to be perceived as benign. That is, it needs to seem okay, safe, or acceptable. Research in HuRL has highlighted three ways that a violation can seem benign: 1) Alternative norms (e.g., one meaning of a phrase in a pun doesn’t make sense, but the other meaning does), 2) commitment to a violated norm (e.g., men find sexist jokes funnier than women do), and 3) psychological distance (e.g., “comedy is tragedy plus time”).
Note: I think that he probably says that sensitive men don’t find sexist jokes funny–empathy that we should be aware of and encourage. Thanks.