Just saw a story on tonight’s news about flooding in Washington state. It included video of salmon swimming in the shallow water across the highway.
So I proposed the above question (the thread title) to my wife, who couldn’t come up with a punchline. I’m leaving it to you to complete the (not so) obvious joke here.
This happens every time there’s heavy rain and the Skokomish River floods its banks. Here’s a picture of some chum salmon probably trying to get across Highway 101.