It's always the creepy little kids
"Get me the sugar!" called Jack's wife. His heart skipped a beat as he stood before the cabinet. Holding his breath, he slowly opened it.... Dangit! A baby!
The PCs find a small green glass bottle, something can be seen writhing within the smoked glass. If the PCs open the bottle a repulsing form of life will pour forth and grow in size. A genderless beings of soft pliable purple flesh towers before the PCs, it has no detail, no distinguishing characteristics except for a narrow slit for a mouth that holds rows of inwardly curving teeth.