Look at some of these messages. There are names which are unlike the sorts of tags you usually see, as well as some more... creative... inscriptions.
"Christian Francis Huff 5.25.90"
"Sgt. Kevin Fairchild 28 Aug 94"
"Wendell G 10.10.2000" (Who names their kid "Wendell"?)
"6th Coast Artillery Regiment"
"Beware the beast cometh"
"THEY STOOD STRONG & PROUD
PATIENTLY WAITING TO PROTECT OUR SHORES
THE MASSIVE GUNS ROARED LOUD
BUT NOW ALL THAT'S LEFT IS FOLKLORE
FOR ANY SHIPS WERE BOUND TO BE POUNDED
ALL YE WHO ATTACK OUR GOLDEN GATE
HEED WARNING! AND MEET YOUR FATE
"You may not realize it, but I am standing behind you" [chalked on wall below blackboard, visible in previous picture]