I wouldn't care for a kid who did this. There are certain things you can NOT control with kids and that is what goes in and what comes out. If I can not curb the behaviour then I won't care for the kid.

My kids here behave because they know that I am in control and they trust that I will meet their needs and take care of them. A kid who vomits on cue is the one in control. That won't work for me.