I smiled. I felt really virtuous, glad that I'd been able to help, happy that my sacrifice would perhaps save the life of someone else, pleased that because of me, because of my willingness to lie there and have a pint of life-giving fluid taken, because of my philanthropic ideals and my desire to help my fellow man, I could rest easy, knowing that I'd done my bit.
Then I thought ...
Hang on. WHEN DID I GIVE BLOOD?
As far as I know, I haven't given blood today, nor have I ever.
Or ... do they know something I don't?
Have I been visited? Aaaaaaaaarrrrrrrrrrggggggggghhhhhhhh!