A variation on The Stranger. Involves, in addition to sitting on your hand until it becomes numb, also painting the nails on that hand. You then have a seat in a dark room or closet and use your free hand to shine a flashlight on the hand with the painted nails while you masturbate.

A jack off buddy (from 'cum' /'come', meaning 'semen', and 'companion'); a friend that you get together with for sessions of solo or mutual masturbation
Variant of: cumpanion (from 'companion' & 'cum'); jack off buddy & wank bud & JO buddy
Similar to: fuck buddy

When a man paints the nails on his non-dominant hand red, sits on this hand until it goes numb, raises one leg (same side as hand), reaches under raised leg with non-dominant/painted hand and proceeds to jerk off. (the Ultimate Stanger can be performed sitting or standing) GIDDY UP!

When, after having two non-functioning arms for a period of time, you have an arm transplant procedure and use the new arms to pleasure yourself.

Note: This has to be done before full nerve growth occurs or it just isn't "ultimate".