Some people were confused by it.
England got off to a great start against Nigeria today, taking the lead in the 6th minute through a Gary Cahill header. However, the most notable moment of the opening stages came when Dele Alli was loudly booed every time he touched the ball.
It wasn't clear initially why he was booed by the away fans, who had travelled to Wembley in big numbers. Dele hadn't hit anyone yet, or dived to win a penalty, so what could have angered them so much?
As it turns out, the boos are thought to be the Nigerian fans' way of venting their frustration towards the Spurs midfielder for choosing to play for England instead of Nigeria.
He was born in Milton Keynes to an English mother and a Nigerian father, with whom he famously has a complicated relationship.
Having dual nationalities is a complex and deeply personal thing, and footballers really shouldn't be berated for choosing one side over the other.
It's also possible, although unlikely, that there was a large Arsenal contingent in the away end, there to support their player Alex Iwobi, and they were taking every chance to boo a Tottenham player.
Dele didn't allow the boos to get to him, though, and put in a solid performance in the centre of the pitch, combining well with Harry Kane and Raheem Sterling ahead of him.
