backseat thuggin'

it's not a thing it's an activity. what you must do is:

1. sit somewhere towards the back of a gathering of people (ie: a classroom)

2. often times you either must look really cool or really threatening, often giving dirty looks at a speaker

3. can only be done in a public gathering (ie: a class, lecture, public address)

Jack: hey, Alex, Steve looks pissed.
Alex: Naw, he ain't pissed man, Steve be backseat thuggin'.