MOUNT VERNON, Ia. — When it rains on RAGBRAI, it divides the riders into two distinct groups: those who hunker down and those who dance it out.

Stacey Jackson of North Liberty fell into the second category, as did hundreds of her closest friends in the middle of First Avenue. Sporting a pirate’s eyepatch and fake mustache, she downed a can of beer with the aid of some plastic finger-puppets designed to look like tiny hands. (Kristen Wiig used a similar gag on “Saturday Night Live.”)

This year’s unofficial RAGBRAI anthem, Mark Ronson and Bruno Mars’ “Uptown Funk,” pumped from speakers at a nearby bar while revelers showed off their best moves in a swirl of boozy, rain-soaked euphoria.

Meanwhile, the other sort of RAGBRAI riders huddled under an awning across the street. Cassie Grutz of Dubuque held a shivering Pomeranian named Teddy, who seemed irritated — or at least puzzled — by this whole strange human ordeal. Teddy had spent the morning in Grutz’s backpack, but a support driver was coming to fetch the dog and take the poor beast to a dry RV.

The rain cleared off by 1:30 p.m. or so, when riders started to peel off their ponchos — or pluck off their tiny fake hands — and head down the road.