It is a korean swear word meaning son of a bitch. Ge means dog and seki means child. However, you can't literally translate it into english and say YOU DOG CHILD because that doesn't sound like a fucking swear word. The implied meaning is son of a bitch.
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.