The other day, Summy pretended to be the mommy while I was forced to be the baby being put to sleep. When she was tired of the game, she said "Now I'll be the baby and you be the rubberback."
Rubberback (noun): one who rubs somebody's back or tummy, in order to put them to sleep.
I do add those "ie"s to the end of words to make them sound cute - doggie, fishie, froggie, etc. When a car next to us honked last week, Summy said "Did you see that car-rie?" When I said yes, she said "Did you hear that car-rie make the sound-ie?"