Tying a sock on a doorknob to signify to others that you are inside the room having sex. You do this as an international sign to say: do not enter. If you do, you will regret it and I will be embarrassed.
Sometimes called a doorsock
Spock On is friendly phrase similar to Rock ON, or Hello, Good Job, Cheers, Etc. The term is often found used by players of the game Mafia Wars. The origins of the name come from the team at Spockholm that coined the phrase to unite its fan base.
When you're sitting on the top deck of the bus and you see a sock on top of the bus shelter.
You don't really know how it got up there and what is it doing up there. The sock have elevated beyond its ability to function, and you just wonder what kind of dumb arse put him there to begin with