What is "grass green"

Richard Eugene "Grass" Green (May 7, 1939 – August 5, 2002) was an African American cartoonist notable for being the first black participant in both the 1960s fan art movement and the 1970s underground comics movement. In the 1960s, Green's Harvey Kurtzman-like zany, action-packed, humorous comics parodies appeared in numerous fanzines. His "outrageous" 1970s and 1980s underground work used searing humor to expose America's racism and bigotry.