They used to put the babies inside the King Cakes, but several years ago it was determined that that presented a choking hazard.  Now they just put them in the box.  If you find the baby, you either have to bring the next King Cake or throw the next Mardi Gras party depending on where the King Cake is served.  We have an administrative assistant where I am consulting that rides a Mardi Gras float in New Orleans every year, so she has been travelling to New Orleans every weekend for "practice" and bringing a King Cake to the office on Monday.  I have yet to "adopt" the baby!