It means doing assignments FAST
I am Speed assignmenting
A blowjob dat a "dirty old man" highschool-teacher or college-professor requests from one or more hot-chick students in his class in exchange for a passing grade in public-speaking.
Da term "oral assignment" could also refer to a schoolwork-related directive whereby either (1) a teacher of either gender catches a pair of students in his/her class performing fellatio on each other, and so said educator makes one or both of said "busted" academic lovers perform an extra/unscheduled public-speaking session as a bribe for da teacher's "keeping mum" regarding said scandalous incident, or (2) a female teacher lets a male student's face venture under her skirt and/or blows him, but also makes him "earn" said delightful privileges and/or her silence regarding them by having to perform one or more public-speaking presentations.