Combination of FOCL (Falling off chair laughing), ROFL (Rolling on the floor laughing) and LMAO Laughing my ass off). FOCROFLMAO therefore is "Falls off chair rolling on the floor laughing my ass off".
As a reaction to a funny comment or joke told over the internet.
E.g. Joke Teller: ...so the guy replies, I didn't know your dad was a pharmacist.
Listener: FOCROFLMAO!!!!!
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.