From TechNode:
…we are just now beginning to see what silly creative ways will this technology be applied. The newest example from China is a blockchain-based toothbrush by Shenzhen-based 32Teeth,
Source: The world’s first blockchain toothbrush lets you mine coins by brushing your teeth · TechNode
This brush mines crypto-currency for you while you brush. It also monitors your brushing effectiveness down to the individual tooth. I am not sure if I should label this “just for fun” or “future tech”?