Happy Birthday a few years back I got to see the USMC birthday celebrtion at Camp Pendleton, CA when I was working there and what I remember the most was the cutting of the cake.
The CO cut the cake and gave the 1st piece to the oldest marine present (in terms of USMC "years") and the 2nd piece to the youngest marine present. The first one was to say thank you for his many years of service and the 2nd piece was to show the youngest marine the torch he now bears.