Last time I donated blood was 15th March 2012. I deliberately timed having a tattoo done afterwards, and had it done on the 17th. The idea was that I'd miss minimal donation drives after that.
I've had a letter today, that says next one in my town is on March 14th. This is a few days before my '12 month' cut off period that they ask you to leave after having a tattoo.
AIBU to be considering going along and claiming it's been more than 12 months, or would that be really fucking stupid and dangerous?