Metaphor doesn't seem like the right word

Meantime, people are calling Sarah Palin’s six-year rise from part-time mayor to V.P. nominee improbable, but people who say that have a poor understanding of probability. Sarah Palin’s election as governor was improbable: getting hit by lightning. The fact that she might be vice president is more like getting hit by an asteroid and yet surviving because the asteroid has a hole in it shaped exactly like Sarah Palin.

Welcome to the Palindrome by Kevin Guilfoile & John Warner - The Morning News.