Prior to Christ's crucifixion, he fathered a child whose subsequent descendants have been protected throughout the centuries by the Grail.
Eventually, this descendant was born (the 45th great grandchild) and suffers mental and physical complications from roughly 3000 years of inbreeding.

His actual name is not known, but he refers to himself using the nonsense word "Humperdoo".
Humperdoo is hidden in a heavily-guarded, top-secret location and was lucky to be born in the bar part instead of the grill part on "Murphy's Bar & Grill"