Not that you'd really need an explanation for shifting Ryan Reynolds, in fairness, but nevertheless Andrew Garfield was good enough to provide to Graham Norton on last night's show.
In a nutshell, the reasons were pretty simple - Garfield told him to do it if he won and, more pointedly, he said to do it and then sorta break off from it. As we know, Gosling won instead and, yet, he and Garfield did it anyway because, well, who knows and who cares?
The look of shock on pretty much everyone's face was reward enough. Here's Gosling originally finding out about it, originally...
And here's Garfield's explanation as to what exactly happened on the night.