A combination of the stranger and the reverse stranger. In the double stranger you sit on both your member and your hand, before masterbating. Then it's like you're watching someone else get a hand job... You're just a guy in the room watching.
Last night i gave myself a double stranger... it was good.
A variation of the stranger. The act of siting on your dick until it becomes numb, and having your partner sit on her hand until it becomes numb, then she proceeds to jerk you off. This gives the illusion that you're both watching someone else give and receive a hand job.
Rather than throw in my favorite porno flick, my girlfriend insisted that we do the double stranger. She says it's like watching the porno live in person.