A DSA is a D*ck Sucking Appointment wherein a person, usually a college student in large classes visits his/her professor excessively for any personal motive.
Guy 1: Heyy! Where have you been?
Guy 2: I just visited Prof.H during his office hours.
Guy 1: Damn! you gotta chill with the DSAs man!
Guy 2: I need this "A" to boost my GPA.. gotta do what i gotta do you know!