My son has been using pronouns for a couple weeks. “My this” is his new favorite way to lay claim on any object.
His brother picked up the phrase quickly and now they can sometimes be heard arguing “My this.” “No, My this!” … and so on.
Sometimes I have to step in and confiscate the object if its is causing too much strife. I say “My that.”
When I first demonstrated the new pronoun Twin A thought it was funny and smiled. He understood the word but it took a few days for him to integrate the phrase into conversation. Now they use that phrase too.”My this.” “No, my this. My that!”