First of all, it is not secure to attach an USB stick to another PC where you don't know the security standards.
Anyways: Check the "datadir" command line setting (maybe with relative paths like . or ..).
As you need internet connection at your frined's place anyways, I'd recommend an online wallet with a bit of "cash" - you don't carry your whole savings account with you if you just want to buy an ice cream too, right? Alternatively you could set up a second bitcoin client on that USB stick and only transfer a bit of money there.
Well.. people carry around their bank debt cards which allows them access.... or a certain amount of cash. I want to do the quivilant with btc.
Yes I realize your security point and obviously I would be carrying around an amount on this stick that I am comfortable with not some
ginormous amount of coin. I don't have a ginormous amount.
I'll check into the above guide I just wanted to understand if/how this could be done.