In a home of 3 little ladies, you can bet that 'playing house' is top on the list of things to do. They often have every doll and stuffed animal out, thus each having extremely large 'families'. They play what they see - everything as 'real life' as possible.
So, last night I notice Robin cutting smallish bits of black construction paper. Didn't pay much attention. I'm used to her itty-bitty messes. Next thing I see is her pulling a diaper off a doll with...the black construction paper stuffed in it. Hmmm, if only real poopy diapers were that easy to clean up. She did all the antic of a messy, smelly diaper though. "Ew, gross, baby, you stink."
I'm sure that one was a learned trick from her big sisters and, wow, aren't they creative?