Wearing White Socks
This is another huge giveaway. Here in the US, we may pick on people for wearing socks with sandals, but odds are the socks themselves are a giant white, uh...red flag whether you're wearing them with sandals or not. People across Europe and in the UK tend to wear darker socks, and if you're wearing those white numbers—especially if you've got them pulled way up onto your calves—you're an American.
Ken
Bill