I am not making this up

A catchphrase of Dave Barry's, alternately said when he writes something wild but true, or when he writes something wildly made-up.

A catchphrase added onto to the end of a narrative to either:
make a story more amusing (see forced-Lettermanlike irony) or make a story more interesting by adding 'truthiness' to it.
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The 90s equivalent of truth is stranger than fiction
Often used in place of: truth is more amusing than fiction
not to mention, Life imitates art and Why would I make this stuff up? or Who makes this stuff up?

I don't think Dave Barry has ever used "I am not making this up" when he really was making something up. He even addressed this in a column. "No, I really am really not making it up," he said, when somebody asked him whether or not he really made stuff up and then claimed it as truth.

It's a shame real journalists can't be held to the same standards. (Okay, that's not strictly fair, but omission and inaccuracy, whether by ignorance or malice, can hopelessly skew any issue.)

Anyway, I believe him.