over the hill

We're at the Ranch in California. Amanda and I are sitting under a tree watching the kids play in the trailer where we are staying. They are playing with their cousin Clint and they seem to have found a sign that says "Over the Hill". Julian came out of the trailer with the sign and waved it around saying "we are an Amtrak train, we are ready to go. We are going to go over a bunch of hills". Funny that a 7, 5 and 4 year old are holding up an Over the Hill sign without any idea of what it means to the rest of us.