When you look at Jewish humor, for the most part, the jokes are quite layered -- they build up and eventually show some sort of logical inconsistency -- and a lot are philosophical. (In the broader culture) a majority of jokes have an aggressive component, a scatological component, or a sexual component, but Jewish jokes work through understanding the absurdities of the logic.Of course, there's Joan Rivers and Don Rickles. Triumph the Insult Comic Dog. Estelle Getty's character, Sophia Petrillo, on The Golden Girls wasn't exactly nice. She was loved in part for deflating the egos of her targets when they annoyed us. Notice how farts are euphemized as "emissions" here. At once it may be cruder than a lot of other humor popular among seniors --my guess, anyway, being not that old-- but it's softened in the telling rather than being reserved for suitable company. Mankoff's wrong to imply that Jewish humor excludes the aggressive, scatological, and sexual components.
But Mankoff is right about what Jewish humor does include. It's rarely simply crude or simply silly. We don't understand Adam Sandler's humor as "Jewish humor" even though he has turned increasingly toward Jewish themes -- with the help of "Jewier" comics like Judd Apatow and Mr. Triumph himself, Robert Smigel, on Zohan. Maybe the problem is that we only identify the best Jewish humor as "Jewish humor," but I doubt Sandler would cite the same Borscht Belt influnces Smigel constantly references.
On the other hand, with Apatow and his gang of filmniks, Jewish humor has emphasized a great deal of silliness and crudity. (I'd say it assimilated or even appropriated these qualities, but they were never absent.) But it still focuses more on the absurdities of logic. Jason Segel's character in Forgetting Sarah Marshall doesn't get dumped while naked because penises are funny but because it highlights the absurdity of social ettiquette. "Would you like to pick out the outfit that you break up with me in."
There's a world of difference between Sarah Silverman and Andrew Dice Clay. It's not the same difference as between the New Yorker and the Diceman.