Eli says - What is that noise??!!

In the wee hours this morning, Eli was woken to a new noise he has never heard before. I walked into the boys room while Eli was asleep to change Aiden's diaper. Aiden was fussing and as I was about to walk out of the room, Eli sat up in bed with a look of confusion on his face and said, "WHAT is that noise?? It's not even morning yet."