One of my favorite stories that can provide proof of personhood revolved around his career as an artist. Lynn experimented with paying Chantek for his art. He received poker chips for creating more mobiles and could spend those on his favorite treats. Chantek, being incredibly strong, hit upon snapping the chips in half to double his purchasing power. Lynn responded by switching the legal tender from poker chips to metal disks. Chantek did not let it rest there. During his walks with a trainer he began to collect bits of foil along the way, being very careful to not let the trainer see him do it. At night when he was alone he fashioned his foil collection into metal disks. Counterfeiting is a high-order function no matter how you cut it. It was an elaborate plan requiring secrecy and the focus to stick with the plan over a period of weeks. Chantek had a concept that he was doing something dishonest but moved ahead with the plan and risked the consequences. It is the kind of thing persons do.
In the picture above Chantek is in the middle of signing what he would like Lynn to do. Yes, his sign language can be understood by other signers and he's a lot better at it than me. When we chatted he must have been frustrated by my poor language skills but he always was patient with me.