On a recent visit to our house, my mom ended up with a small pickup truck of Anthony's in her sweatshirt pocket (presumably he gave it to her to hold on a walk or something). She found it when she returned home (about 2 hours away by plane). She told him about it on a video call as if it were a funny story, "Guess what I found in my pocket?" and she held it up. He immediately started crying hysterically. She promised to bring it back next time she visits.
Since then, Grandma and Grandad have been called thieves and criminals and bad guys. Grandad (my dad) eventually convinced Anthony that he hadn't stolen it, only Grandma.
For weeks if you asked Anthony how he was feeling, he might say, "A little sad." When asked why he felt that way, he said, "Because of my pickup truck. My favorite pickup truck. Grandma took it." (As far as I can tell, it was not a favorite pickup truck and he didn't he didn't even miss it before Grandma found it and told him about it.)
Almost every time he talks to my mom he asks to see the pickup truck. When they traveled somewhere else, he asked if they took it with them (they did not).
Meanwhile, Anthony left a small Sheriff car at his other grandfather's house. He knew he was missing it before we even left their house (it was eventually discovered under their couch and he got it back the next week...it's one advantage of only living 5 minutes away by car and visiting every week). He told my mom about it and she asked if these grandparents were also criminals. They were not.
Recently, my dad asked Anthony if he could keep the pickup truck. Anthony said, "Sure!" Apparently, you just have to ask nicely to get a different reaction. Just don't be a criminal.