1. Befriend a rock.
2. Buy a clever disguise.
3. Become familiar with the rock’s patterns, such as what bar it frequents after work and what blood bank it makes withdrawals from after becoming tipsy and unfocused at said bar.
4. On a night when moonlight is dim, follow the rock to its watering hole.
5. Act friendly by buying it enough drinks to make it tipsy and unfocused. Say things to give it a false sense of security and invincibility — like, “You are such a rock.”
6. Anticipating when the rock will be ready to leave the bar and stop at the blood bank on its way home, dismount your bar stool 15 minutes ahead of that time, announce loudly enough for at least three future witnesses to hear you say, “Well, it’s time for me to get my drunken ass home. I am so loaded that the only thing I will be able to do is drive directly home without stopping anywhere or having social encounters of any sort.”
7. Once outside, sneak into the unlocked storage shed at the rear of the parking lot. Change into clever disguise.
8. Lurk in the dark, maintaining a safe following distance from the rock, which has now left the bar and is approaching the blood bank’s ABM (Automated Blood Machine).
9. Once a bag of blood has been dispensed, beat the rock into unconsciousness and steal its bag of blood. Do not worry about taking the receipt — it’s not your responsibility.
10. Remove and discard clever disguise and go on your way with your ill-gotten booty.
By the way, why do you need a bag of blood, anyway?