One of my first book reviews, in 1995, was of a James Thurber biography for the Boston Phoenix. Thurber was one of my childhood heroes, which shows you how many friends I had as a kid. After the review ran, I got an indignant postcard from Dave Barry in which he said he had no choice but to use the phrase "I'm not making this up" to let his readers know fact from fiction. This was before the "fabulist" scandals involving nonfiction writers like James Frey and Augusten Burroughs, which eventually nicked humorist David Sedaris. So Barry had a point, but I still think humor reads better without the "this is exaggerated, this is not" signposts (and I defended Sedaris on this point).
An excerpt from the Phoenix review:
Today's most popular humorists may work in the vernacular, but they share little else with Thurber. Bestsellers by Jerry Seinfeld, Tim Allen, and Ellen DeGeneres retain the staccato style of their stage performances. The publishers of these books could help us out by sprinkling throughout the text little battery-operated laugh tracks (just like those electronic greeting cards that sing "Happy Birthday" when you press a button). And though most of these comics echo Thurber's "little man" persona, trying to cope with bull-headed authority figures or the baffling behavior of the opposite sex, we still sense the confidence of people able to bare their souls in public and not hide behind the printed word.
Even humor writers who didn't start out on the stage now adopt the ironic distance of a Letterman or Leno. Dave Barry constantly winks at the reader in the same way David Letterman smirks and plays with his tie to get a laugh when a joke falls flat. For instance, Barry likes to insist, sarcastically, that he is "not making this up" in particularly fanciful columns. Thurber invented half the stuff about his family in My Life and Hard Times, but he had the sense not to go on about it in print.