The phrase "dead ringer" comes from Old Medieval England when someone was pronounced dead they were quickly sent for burial due to no refrigeration in mortuaries. This led to some wrong diagnosis and the burial of people who were actually still alive. Many a resumed coffin has been found with server scatch marks on the inside. A contributor of this was the fact that
beer, when
drunk in large quantities from the old "lead
beer mugs" made the thirsty person not only
drunk but the appearance of being dead due to the fact the the chemical reaction between the
beer and lead slowed the heart beat of the said thirsty person to such an extent that an over enthusiastic dockter
may pronounce the drunkard, dead. However, if they were not buried so swiftly they would in fact wake up with no more than a regular and deserved "hangover". Once this was realized and before there was a
ban on drinking out of the early
beer mugs made of lead, people were buried with a bell so that they could ring it if they were to wake up while 6
feet under. This is also where "saved by the bell" comes from.
During a race or any gaming
activity where a particular "unknown" participant excels, they can be termed a "dead
ringer", in other
words they are back from the dead.