Jose Mourinho offered his Chelsea counterpart Antonio Conte some lengthy words of wisdom after seeing his Manchester United side slump to a 4-0 defeat at Stamford Bridge, with some reports saying he was lecturing the Italian on his touchline conduct.
Here, we consider some other lessons from the Mourinho book of etiquette.
Working up a home crowd at 4-0 might be beyond the pale for Mourinho, but he has never had a problem with pumping up his own tyres.
He will forever be remembered for anointing himself as a "special one" upon his arrival in England, but it was hardly a unique incident and he has never been shy of trumpeting his own achievements.
"Why have Chelsea suffered so much since I left? Because I left," he said in 2009.
DON'T lose perspective
Speaking a decade ago, Mourinho claimed the only thing that was troubling him came from north of the border. Rather than a reference to then Manchester United boss Sir Alex Ferguson, it was a sickly swan that had caught his attention.
"For me, pressure is bird flu," he opined. "I'm feeling a lot of pressure with the problem in Scotland. What is football compared with life? A swan with bird flu, for me, that is the drama. I have to buy some masks and stuff."
DO celebrate important goals
Mourinho's first major impact on English football came when his unfancied Porto side knocked United out of the Champions League at Old Trafford.
An injury-time goal from Costinha settled matters and the young manager leapt to his feet, racing along the touchline in joy as his long black jacket fluttered like a cape behind him.
Presumably Conte would have been forgiven for such a reaction had Chelsea's victory on Sunday been more marginal and come later.
DON'T be quiet in the stands
Such was his position of strength at Chelsea in 2014, Mourinho felt bold enough to breach one of sport's oldest commandments: thou shalt not criticise your fans.
After securing a 2-1 win over QPR, the Blues boss said the atmosphere created by a crowd of almost 42,000 people was akin to "an empty stadium".
DO be quiet in the stands (if you support the other team)
Never a favourite of the Liverpool fans, Mourinho's relations with the Reds dipped to new lows during the 2005 League Cup final.
Liverpool were on course for victory in Cardiff until Steven Gerrard's own-goal drew Chelsea level. Mourinho ostentatiously raised his finger to his lips in a silencing gesture - earning himself a touchline dismissal.
He later indicated his message was meant for the media, but that explanation never quite landed.
DON'T criticise colleagues for doing their job
Mourinho was visibly irate when club doctor Eva Carneiro and physiotherapist Jon Fearn treated Eden Hazard late in a drawn match against Swansea, claiming the pair's actions were "impulsive and naive".
It was a row that simmered on and Carneiro, who was demoted and later left the club, settled a case for constructive dismissal and sexual discrimination.
There was no official statement from Mourinho but Chelsea said they "regretted the circumstances which led to Dr Carneiro leaving the club and apologises unreservedly to her and her family".
DO prove your ethical credentials by spending vast amounts of money
As he prepared for Chelsea's ill-fated title defence at the start of last season, Mourinho considered the merits of adding some big-ticket items to his squad.
Nothing unusual there. But instead of couching his ambitions in terms of necessity or sporting investment, he chose to paint his planned trolley dash as a point of principle.
"The board has worked so well over the years in making money with sales that if somebody has the right - the moral right - to do that, then I say that Chelsea is one of them," said Mourinho.
DON'T neglect your family's nutrition
Mourinho has a fractious history with Rafael Benitez, but aimed a particularly personal blow in the Spaniard's direction after quotes emerged from Benitez's wife, Montse.
Mrs Benitez reportedly said her husband was used to clearing up Mourinho's messes, having taken on jobs at Real Madrid, Inter Milan and Chelsea.
Mourinho's response? "I think the lady needs to occupy her time, and if she takes care of her husband's diet she will have less time to speak about me."