Football has so many rules and regulations these days that it's hard to keep track.
A last man foul used to be a straight red card and now it's not. Backpasses used to be fine and now they're not. Tackling Cristiano Ronaldo used to be fine and now it's not. It's a minefield.
But we thought the art of celebrating against your former club (or the Adebayor Rule, as it is more commonly known) was forever sacred.
https://twitter.com/FootballScenes9/status/410492647665844224
Of course, the muted celebration (or #mutedcelebration, to give it its official Twitter name) is nothing new, to the extent that we've seen players make a point of not celebrating against former clubs, clubs they almost joined, or clubs whose kits they sort of like.
The natural conclusion is for a player to buck the trend and celebrate against a former employer, only to see fans come down so hard on him that he feels the need to issue a written apology. No, really.
That fate befell Allan Nyom, the West Brom defender who joined from Watford over the summer. And the best thing? He's not even the player who scored the goal in question.
'I just want to apologise to the Watford fans because, unfortunately, it seems that my celebration during the Saturday game was considered as a lack of respect,' Nyom wrote after Albion's 3-1 Premier League win.
'Sincerely, it never was my intention to disrespect the club or the fans, and I apologise to them if they have felt it.
'In my heart there is only gratitude and my best wishes for all Watford FC family.'
https://www.instagram.com/p/BNrhkqnhdz8/?taken-by=allannyom&hl=en
Nyom, who played 37 times for Watford last season, had spent his entire career at Pozzo family-owned clubs (he previously played for Granada on loan from Udinese) before moving to the Hawthorns.
The Cameroon defender has made 10 appearances for Tony Pulis' side, who've made a surprise run to 7th in the Premier League table.
Catch up with this week's episode of Football Friday Live
