Option 1: Go to one town maybe 20 minutes away, take my books back to the library, check out a few more, go donate blood, and then buy a new pair of shorts.
Or
Option 2: Go to a different town that's 10 minutes away, take my books back to that library instead, check out more from their better selection of books, go back home and continue my mundane existence. [plus, their parking lot is so much easier to back out of than the other library and I'm a fairly n00b driver]

It depends who much you need shorts. If you need shorts, then go do #1. If you don't, go with #2. I doesn't really matter if you give blood or not, because if you can, do it, but if you can't, no big deal. And if you want to be safer, go with #2.

Me personally, I would do option 2, then go get shorts. Partly because I would want the better parking, and then I would go the the shorts, because I do need the shorts.