When you put a large gauge needle in your forearm vein and pull the syringe out , leaving your vein open and a large stream of blood pouring down your arm.
You then proceed to masturbate with the blood as lubrication. You may only remove the needle after you cum.
can be done with both arms if you have a partner.
"sorry sir my son cant make class today, he was double leeching last night and lost a fair amount of blood"