Credit Cards

[Daisy]

OK, this is utterly *utterly* off-topic, but it is something that has 
been bugging me for a while, and since there are plenty of Americans 
on here, I may get an answer!

When I was watching the Oscbournes the other day, Kelly borrowed 
Ozzy's credit card, *without him knowing*, and went off shopping.

How does that work exactly? If you did that in Britain, you'd get 
arrested as soon as you tried to use it. I've heard this mentioned in 
other US films, usually of the 'teen romantic comedy' variety(!) and 
it has always confused me.

Anyone?

Jules