Well, THAT'S easy. Surprised that you haven't thought of it already, seeing as you've been our brother for so many years and seen so many of our pranks.

You just vanish all his clothing and the bloody thing would fall the ground and then you Accio it to you.

The only problem with that idea is that then you'd all have to see his bloody bits. And he'd probably kill everyone in the school before you could cast the Fiendfyre.