I just discovered it today, he was on my lap and we were having play time and i was singing to him etc we were being happy! Then my partner told me something about the band we wanted for the wedding not being available so i did a big sad face and the baby did a sad face and cried! I picked him up and smiled at him and he was fine instantly. My partner tried it a minute later and baby cried again. Has anyone elses LO done this? It is so cute! (I won't do it again though as it's also sad to see him upset!)
I suppose it does make sense as he will laugh when i laugh and smile when i smile etc!