150
Three million malware-infected smart toothbrushes used in Swiss DDoS attacks
(www.tomshardware.com)
Rules:
Act like a nice human being.
So it can track how often you brush your teeth and sell that data to insurance and toothpaste companies, and then spam you push notifications to buy more toothbrush heads.
Anything useful to the user could be done via Bluetooth or something. WiFi is solely for the benefit of the company.