What does this word mean?
Even though I watch a lot of BBC crime shows, somehow I was not familiar with the term "Grass." I would appreciate it if someone could help me out.
He walked rapidly, going nowhere in particular, but every road in Brighton ended on the front. I’m too old for the game, I got to get out, Nottingham; he wanted to be alone, he went down the stone steps to the level of the beach; it was early closing and the small shops facing the sea under the promenade were closed. He walked on the edge of the asphalt, scuffling in the shingle. I wouldn’t grass, he remarked dumbly to the tide as it lifted and withdrew, but it wasn’t my doing, I never wanted to kill Fred.
----Brighton Rock by Graham Greene