Every culture has its foibles, which stand out to others.
For example, in the North of England we tend to carry our jackets, even if it's too hot to wear them (effectively using the jacket as a bag) rather than go out without them.

Many's the time I've been ID'd as a Brit because of this (ie before I've opened my mouth so not the accent and not the clothes as I generally buy my clothes in the US - apart from my fetish for fitted shirts from Jermyn St.)

But hey - it might rain