This is short for a sock puppet substitute. As you'd imagine, it refers to a sock puppet being used in place of an absent person or subject. At the time of my writing this, there is only one Google search result for the word sockstitute.

The act of extreme masturbation. You must "knock one out" whilst in close proximity to any of the following; Your mum, a nun, your boss, a member of parliament, George Michael. A person with capabilities to act upon catching you mid self-abuse obvisouly ups the ante. Ejaculation must be reached before your danger wank target comes (no pun intended) to investigate. The higher the chances of being discovered with one's pants down, pulling one's war face is obviously where the danger comes from. The more danger involved the harder (or softer) it is to complete the task in hand (snigger). The more dangerous the better. The chance of being arrested, pummeled by an angry father or having your hand severed by an arab's sabre means that you are a pro "Danger wanker."

One who trades sexual favors for socks. Boyscout socks are traded for currency among campers across the country. Young girls would kiss or flirt with Boy Scouts at camps in order to acquire their rare, standard-issue socks.