In Which A Digit Takes On A New Significance

As we all know, sometimes, for a good cause,
I let some strangers take from me a pint
Of blood. The process still does have some flaws;
The pain, the fainting, in my case the fright
Of needles. Still I do it and I'm proud.
I've given gallons three as of today!
In doing so I'm part of a small crowd.
'Twould be much bigger if I got my way.
It's not so bad, but this time I've a gripe:
The finger that they tested really hurts,
A grave impairment when I have to type,
As right now. It's the one used for alerts
Of one's displeasure, called the "naughty" one.
Is this my punishment for having fun?