(That photo originally taken by Mike "Culture Pulp" Russell, photoshopped by R.D. Pollard. The photo's subject, D.J. Cort Webber, was, as you can see in the original photo, pretending to stab. Now it's easier to pretend.)
This is posted to LJ by someone who gives blood the right way, and likes to encourage others to do so, too.
(I love that this happened: two weekends ago I was at Seattle's Emerald City ComiCon, where I last donated blood. I wore my bandage while wandering the con. A guy dressed up as blood-splattered Ash from the Evil Dead films saw me and said "I should donate blood!" I hope he did. I hope that others did.)