Pick a size, any size.

[bilblio.livejournal.com]

Right girls I need some help.
How do you subtly find out what size someone is so you can make surprise presents?

I want to make some fingerless mittens for a mate. He's got tendenitus, so he's got to rest his hands and keep them warm. This is a huge hardship for him because he's a computer techy, and he plays piano.

So how can I find out what size he needs without him twigging what I'm doing?

What creative ways have you lot come up with to find out peoples sizes?