When a parent is unknowingly cockblocking their kid by being home. The parent is at home, leaving the kid and his girlfriend with no place to get it on. Therefore the parent is obliviously cock blocking.
Matt's Friend: "Yo Matt, did Katie come over last night?"
Matt: "Yeah, but my parent were being complete oblivious cock blockers!"
The opposite of situational awareness. Having no clue what's going on around you. Straight-line thinking - aware of your world and its goings ons only.
Sheilaalmost ran over a biker because of her situational obliviousness.
Mike called the boss a stuck up turd when he was right behind him. That situational obliviousness has him working the weekend.