What does the following idiom mean: "Tinkle contest with a skunk". And where was this idiom first used ? Does anybody know the origin??

Example:

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> Yesterday, in an unsuccessful attempt to discuss government funding with President Trump, Vice-President Pence, and Chuck Schumer, Nancy Pelosi sat down for a hellish 17-minute-long meeting. It was, in short, a mess — a fact that Pelosi conveyed to a reporter using a very interesting phrase.
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> “It was so wild,” she told CNN’s Manu Raju of the interaction. “It goes to show you: You get into a tinkle contest with a skunk, you get tinkle all over you.”
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> Hmm … indeed. To many, this phrase seemed strange or unfamiliar; some, having misheard the first bit as “tickle contest,” were extremely confused about why being soaked in urine would be an inevitable outcome. “What,” wrote New York Magazine’s Olivia Nuzzi. “Pelosi introduces world to new idiom,” proclaimed the Hill. But according to Anne Curzan, a linguist at the University of Michigan, Pelosi was simply trying not to be uncouth in her skunk metaphor.
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