Was it viral marketing? OCD? Or was the half-time pie too pungent? A fan at Stamford Bridge became a YouTube sensation after he was pictured brushing his teeth at the climax of Chelsea's match against Manchester United on Sunday.
"Brushing your teeth in a stadium is just weird," judged Gabriele Marcotti, host of 5 Live's 606 football phone-in shortly before David, who claimed to be the tooth-brushing fan, called to explain himself. "I thought to myself, no one is looking," he said, recalling that he didn't have time to brush his teeth before rushing to the game, so put the brush in his pocket and whipped it out for a scrub after 80 minutes of Premiership action.
A concern for oral cleanliness is a far cry from the grubby era when the only inappropriate thing men did on the terraces was urinating on another fan's leg. In the bad old days, supporters doing things other than watching the match used to fall into one category: women dragged to the game under sufferance.
As football fans recalled on message boards and on the radio, there was the case of the woman who spent the whole game engrossed in a gardening magazine, the knitting fan, the West Ham supporter who admitted straightening her hair (at half-time, to be fair) and the fan who sat at Wembley reading her novel rather than watching Norwich win the league cup.
Nowadays the supporters who are not paying attention tend to be members of what Roy Keane famously dismissed as "the prawn sandwich brigade". When you are on a corporate jolly, the contents of your BlackBerry are far more gripping than the game.