the first day of class i sat next to this guy. when he left the room (early, he seems pretty rude) he shoved his extra large sized drink cup under the chair. i decided not to say anything at the time, because maybe he's a new student and doesn't understand. but it happened again tonight. he left the room again, and on his desk he left his cup! it's not like he didn't notice it, he picked it up from the floor and set it there. i picked it up before i left. i can't believe people could intentionally litter like that. i'm tempted to call him out if (probably when) it happens again. i'm kind of shy, but it's an issue i feel strongly about. what would you do? part of me wants to call him out when he leaves in the middle of class, but i think that would make me look bad. should i just go to the teacher and hope for the best?