Dod

[mmottram]

Dod and Doddy are diminutives for George in parts of Scotland. Why?

[Quizmonster]

Think what happened to the name Richard which started as Ricardus...>Richard...>Rick...>the same letters except the 'R' is replaced by a 'D'! The same sort of process applies to William.
Names have undergone massive changes over time, being subject to such shortenings and playful sound-alterations.
My guess re George is that it was probably made a diminutive as Georgie and then the 'J' sounds became 'D' ones (Dod/Doddie) in the same way as the 'R' and 'W' sounds became 'D' and 'B' sounds with Richard and William.

[kick3m0n]

Dode is also used. Pronounced exactly as it sounds.