Tint frosting green with 3 drops each blue and yellow Neon food color. Set aside. Place coconut in resealable plastic bag. Add 6 drops each blue and yellow Neon food color; shake until coconut is evenly tinted.
Frost cakes with green frosting. Sprinkle with green coconut for grass.
For the "tombstones", place chocolate frosting in small plastic bag. Snip off a tiny corner of the bag. Squeeze out the letters "RIP" onto each cookie. Place cookie into one end of each cake. Arrange cakes on serving platter to create a graveyard.