originally derived by assigning a numerical value to each letter of the word "fag" according to it's position in the alphabet (7, 1, 25). each number is then squared, and the sum of these numbers is 662*.
*(unfortunately, the sum of these numbers is not 662, due to a mathematical error by the inventor of the term. but the number stuck anyways)
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.