A screff is a derogatory term for a person who lacks self awareness. This is a necessary but not sufficient condition for being a screff. Unfortunately, this is a fairly loose family of meaning (à la Wittgenstein). Being a screff is indicative of being oblivious to one's conditions, unclear thinking, a reluctance to accept the use of logic in argument, participating in one's own oppression, liking inane pop culture, not realising the effect that ones ideology and action will have on other people and a reluctance to look for deeper meanings than the immediately obvious. It is also secondarily used to denote members of an underclass who have been failed by society and as such have adopted some or all of the above traits.
Derivatives: (adj.) screffy
Horne and Corden
"Why are you acting like a screff, don't you realise what this means?"