I'm a regular blood donor and I do it for free... I'm appalled by the CAG jokes, it's not very funny. I know you guys have too much time on your hand, but a little civility to encourage a much needed donation is appreciated.
For those of you never have donated blood before. There's a rigorous questionnaire before you start and they'll prick your finger to get a small sample to analyze your blood is good or not. It's definitely not one of those things where you walk in and donate on the spot, if you're not healthy, you can't help even you really want to. There's a shortage (almost always) because good O+ and especially O- are rare... When an ER patient comes in and needs blood, there's no time to figure out the blood type, hence O- is used.