Looks like it was a follow up to someone asking an entertaining question during a lecture, which is the best reason to do some science!

According to Victor Benno Meyer-Rochow of the Research Institute of Luminous Organisms in Japan, a co-author of the original 2003 paper, these fecal findings all started with an expedition he led to Antarctica. Although he was collecting samples of local marine worms and tiny terrestrial insects called springworms for further study, he also took copious photographs of the many penguins in the region, which he used in his lectures. During a seminar at Kitasato University in Japan, a young woman asked about a slide showing a penguin brooding on its nest, wondering about the white and pink lines radiating outward. She interpreted them as "decoration" and asked how the penguins made them.

"I explained that a penguin stands up, moves to the edge of its nest, turns around, lifts its tail, and then shoots from its rear, which leaves a 30-40 cm long streak of semi-liquid whitish stuff behind," Meyer-Rochow wrote in a 2019 blog post. "Everybody laughed—with the exception of the questioner. She got red in her face and quietly sat down." (The color of the feces depends on the penguin's diet: if primarily fish, the poop is white. If the penguin has been feasting on krill, the poop takes on a pinkish hue.)

Someone measured enough penguins to find the average ~~butthole~~cloaca size though. I would NOT do that for free..