A combination of the noun nug (a nugget of marijuana;high quality bud) and the participle tron (let us get tronned intoxicated on marijuana) resulting in a word that can function with respect to all meanings given.
When some resigns or retires from a job, they are on "eternity leave". This can also refer to someone who has passed away, especially someone who worked somewhere for a long time, retired/resigned, then passed away later.
Oh I'm sorry, you didn't know that Kelly is on eternity leave? She resigned and moved to Hawaii!
With regrets I would like to inform you that my boss is officially on eternity leave. I will never see or hear them again. Ever.