Grass is the green stuff on the mall and the cut.
CMU hates grass. In the fall during orientation they build a big tent and kill the grass. Then they spread shit all over it and plant new grass. Then in the spring they put up another tent and kill more grass.
One time, particularly in Fall 2009, when the tent was being removed, it was discovered that a stake holding down the ropes was driven through a water main. This caused a 30 foot geyser to sprout up on the Academic Mall, killing the grass around it, and drawing negative media attention to a campus full of problem-solvers and engineers.
Trees are big grass. CMU is somewhat efficient at killing trees too.