A group of people, usually at a high school, who are known for smoking weed.
"Jimmy is my friend, but all he does is smoke weed and act like a dumbass all the time. He's in the grass gang afterall."
The Grass Gang is a group created by 2 lovely young people. It is said to be the best gang ever; better than the Mulch Gang.
“Hey, do you want to join the Grass Gang?”