"Baby Shaker" is/was a game (?) which asked the participant to shake the baby to stop it from crying.
The 99-cent game, which showed black-and-white line drawings of a baby, had the description: "On a plane, on the bus, in a theatre. Babies are everywhere you don't want them to be! They're always distracting you from preparing for that big presentation at work with their incessant crying. Before Baby Shaker, there was nothing you could do about it. See how long you can endure his or her adorable cries before you just have to find a way to quiet the baby down!"
Shaking the motion-sensitive phone meant that the onscreen baby would get large red Xs over its eyes.
It's clear from the red Xs over the eyes that whoever developed this application was perfectly familiar with the potentially lethal consequences of shaking a baby, but still thought it would be "funny" to market this. It wasn't developed by Apple, but the fact that they allowed it to be licensed and posted on their website is an incredible oversight (probably by a bunch of people who don't have babies).