The banter laws doth state that when acknowledging a friend's moment success or happiness, you must also find someway to take the p***.
And so it was that Captain, Leader, Legend John Terry saw his teammate Cesc Fabregas' textbook 'I'm on hol with the missus' Instagram snap and deliver the holy banter one-two.
"Great picture," wrote Terry "not sure about the about the shorts."
Terry, of course, is already established as something style icon, pioneering the 'Unnecessary Full Kit' look at keys stages throughout his career.
But what is he specifically taking objection to in Cesc's choice here? Is it red and black trim? The suspiciously cheap-looking material? The tightness of the shorts, making it look like the midfielder is a little more excited than his wife Daniella Semaan might strictly prefer for a photograph sent out to 9.1m people?
Or is that Terry is an investor in luxury swimwear brand Thomas Royall, the brand tagged into the comment, and now his career is ending he's wants to drum up interest in his business ventures?
It's really too hard to say.