A simple fart microphone would do. Anyone should be able to tell from the sound if their kid is grunting one out or grunting one in.
The only other feature I'd include is a remote-controlled audio of her mother candidly discussing the perils of aging womanhood, leaks, squeaks, & sags. Lets see either of them play happy after a volley of traumatic bizzare-o-guilt medical issues barking out of her crotch.
I told my daughter's first serious boyfriend that if he knocked up my daughter, I'd beat the baby out of her belly and make him eat it. I'm sure he retained that vision every time they were together. I love to be able to help people form their life patterns in childhood. It's how you build artificial ethics.
