Jefferson Smith loves a good political joke. Early last year, the then-freshman Oregon House member from Portland was getting ready for bed when he and his wife, Katy, began bantering back and forth about what might be the ultimate political prank, something that could lighten the increasingly divisive political mood among his colleagues. As Smith recalls, the idea came almost instantly. "What if we were to Rick Roll the legislature without anybody noticing?" he wondered. And that was the seed for what may ultimately prove to be one of the most elaborate political jokes of all time: A nearly two-minute...