I always wanted to, but my blood pressure is very low, so they won't let me.
Once, a long time ago, I had had enough of that and decided that I would show them. So I took some um, central nervous system stimulant right before I went to the blood drive place, and it did raise my blood pressure to the minimum level, and I got passed on through.
But there were a lot of donors that day, and the wait was long, and so by the time they got to me, the central nervous system stimulant had worn off, and I found out why they won't take people with low blood pressure.
When they put in the needle, nothing happened! All around me, when they did this to other people, blood would flow out into the tube and into the bag, but from my arm, not a drop emerged.
So they stuck me again a couple of times in different places, with the same result, and then went to ask a more experienced nurse, who took one look and took my blood pressure, which had, of course dropped to its normal lowness which generally causes them to take it three or four times because I don't look dead.
Anyway, they informed me that for some reason, my blood pressure had dropped since it was checked in the original screening, nothing at all to worry about, they assured me, but obviously, you can't give blood. Not enough pressure there, as you see, it won't flow out!
And of course now, with all the pills, even if it was through the roof they wouldn't take it, it would knock whoever received it onto their butt!
So I must content myself with urging other people to give blood whenever there is an opportunity!