musical: That was giving blood. It is a whole pint. As noted above by someone, a blood test is a small fraction of that amount.
Really, it is not big deal. You just walk in, roll up your sleeve, watch intently as they stick it in, wonder about how dark the blood looks in the vials, and then go eat your cookies and wonder about how many calories they have and if the blood they took had calories in it. (probably it uses up calories to replace the blood, so you have free license to go to Carlos and Gabbys and fress that night.)