Okay, bare with me, this is a bit complicated, but with hilarious results
I was playing as the Byzantine Empire, invading the Iberian Peninsula, and taking out Castille. I totally destroyed them as a nation, and rebels spawned all over their Iberian holdings. The entire peninsula was Catholic, but due to almost all of their overseas provinces being Protestant, Castille converted to Protestant. So these rebels were all Catholic rebels, and once they succeeded, they defected to the Papal States (newly relocated to Bremen after I annexed the original Papal States).
It seems the Papal States weren't doing so well either, so now all their newly-gai Castille ned Iberian provinces sprung up Castilian-culture rebels, which defect back to. This goes on for a while, with me declaring war on Castille every once in a while to get some of those provinces that defected back to them, when this little number happens:
Amazingly, that blue-ish color in the top left is Columbia (!) who got some provinces due to having the Castilian culture. But my personal favorite is Navarra, who declared independence from the Papal States, and somehow got the government "Papacy"! Long Live (Anti-)Pope Enrique III!