The phrase "sack letter" means a written notice given to an employee informing them that they are being fired or let go from their job. Full definition
It could be recalled that the NUT state wing declared an indefinite strike action to register its displeasure at the issuance of sack letters to teachers in the public primary schools. (newsdiaryonline.com)
So...... about tonight's game; Arsenal: hapless, hopeless City: dominant, confident BUT, there's a thing both teams have in common; their respective performances is a true reflection of their manager's abilities... For anyone to still want wenger at arsenal, that person has to really hate arsenal, be a troll, or a consummate idiot (I feel sorry to say this)...... If only Stan would text him his sack letter this night... (he should send it at least twice, along with two emails too..... (justarsenal.com)
I'm not saying Wenger should be fired, but if we keep making the same mistakes in the workplace over something we know is not yielding (not working) for a period of at most two months, we will definitely get that sack letter. (arsenalfcblog.com)