The Shocker is a particular technique used to stimulate the vagina and anus. In this technique, the partner inserts two fingers into the vagina and another finger into the anus. The name of the technique stems from the fact that the digital penetration of the anus can be a shock for some people.
The term can also be used to describe the hand position used for this form of manual stimulation.
The shocker is also known colloquially as a Six Pack (due to its similarity with the way one holds a six pack of beer), Two in the Pink One in the Stink, or Two on the Clit One in the Shit.