What does Boxing Day have to do with boxing?
"bloodletting," c.1400, flebotomye, from Old French flebotomie (13c., Modern French phlébotomie), from medical Latin phlebotomia, from Greek phlebotomia "blood-letting," from phlebotomos "opening veins," from phleps (genitive phlebos) "vein" + -tomia "cutting of," from tome "a cutting" (see tome).
phlebotomy phle·bot·o·my (flĭ-bŏt'ə-mē)
The act or practice of opening a vein by incision or puncture to remove blood. Also called venesection, venotomy.