Daniel Radcliffe is an awesome guy but - maybe this is a British thing? - he can be kind of eccentric: sometimes, he writes on his butt.
Still, you won't catch Daniel Radcliffe writing on his butt without a cute, funny story to go with it...
He told The Mirror about his say-it-with-butt-words moment on set for rom-com What If with Zoe Kazan - involving modesty patches used during nude scenes:
Zoe wrote me a message on her nipple pasties which said, ‘Hi Dan’.
I tried to write, ‘Hi Zoe’, on my bum but I seem to remember trying to do it in a mirror.
My handwriting is not great at the best of times, but trying to do it backwards on my backside wouldn’t have gone well.
Oh well, Dan, you can't be good at everything! I'm always up for a funny Daniel Radcliffe story...