Traditionally, the bodily remains of saints are venerated as relics. But Jesus Christ ascended into heaven, which means no bodily remains… er, remain. Except for one.
Being a Jewish male, Jesus would have been circumcised. And what happened to the… er, remains? Enter the Holy Prepuce, possibly the dodgiest medieval relic.
As with most holy relics, there are many competing versions – probably all fake. Charlemagne gave one to a pope. It was looted when Rome was sacked. Crusaders brought another one back from the First Crusade. At times, a dozen different churches claimed to have it.