Is his speech regressing out of shock due to the recent events or because he's regressing back due to his mother's influence. Like coochie coo is not something you would normally say to a 13 year old.
Actually I still see many families have kids that age that when they're are too sleepy their parents will tickle them up but it's also because the family are cheerful and flippant. Others would leave them to their own device and some would smack their butt until they're up.