I'm stationed here at Parris Island...and wow! Do they go all out! From wearing shirts in your recruit's Battalion colors (red for 1st Battalion, yellow for Second Battalion, Blue for Third Battalion and burgundy for 4th Battalion), to banners with your Recruit's name on it (usually held up during the Motivation Run so they can see when they run by in the morning), to people writing on their cars things like "Parris Island or Bust" and "Congrats to our New Marine PFC Schmuckatelly" etc. Cheering and acting the goof is fine for the Motivation run but frowned upon for graduation. This is a ceremony where your recruit becomes a MARINE and it is really dignified. Applause is acceptable and encouraged...cat calls and noise makers are not.
Congrats on your soon to be new Marine!
Jenna