Blizzard has launched a month-long blood drive to celebrate the release of Diablo IV's second season, Season of Blood. There will be three tiers of rewards that will unlock as more people donate, with the final reward being a sweepstakes for a custom liquid-cooled PC infused with human blood.
6 weeks:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3969546/
Gross, but I don’t imagine anyone would be doing a fluid swap before the one year mark (normally, without blood)