My wife, my two kids and I were at the science museum the other day. One of the rooms educated visitors about heart, blood and arteries. Like with many science museums, there were plenty of interactive devices that demonstrated to kids (and generally less educated folks) the obvious facts about us and the world around us. And so one of the devices had a metal plate with two footprints on it, a stand at the end of the plate with a jar, a huge green button and a sign instructing to step on the footprints and press the button to learn how much blood you have. I stepped on the plate, pressed the button and was happy to learn that I have 10 cups of blood. Then my wife, who is a good 40 pounds lighter than me, stepped on the plate and stated with a giggle that she has more blood than me- 11 cups. When she asked me why she has more blood than me, my comeback was swift: “That’s because you keep drinking the blood out of me, woman”.