How did we come to say "yonks" meaning a long period of time?
"I haven't been to the cinema in yonks."
Etymonline has nothing and Oxford dictionaries has:
noun: British informal: a very long time: I haven’t seen him for yonks
1960s: origin unknown; perhaps related to donkey's years (see donkey)
If it has indeed spawned from "donkey's years", when and whereso?