Hypothetical flag quartering the British and American flags (Lunar Dragon via Wikimedia Commons)
For decades, Brits have complained about American contamination of British English. More recently, the reverse has been taking place: British expressions are elbowing their way into American speech. So far, Americans don't seem to mind.
Listen above for a conversation with two people who closely follow these lexical exchanges: Lynne Murphy at the University of Sussex and author of the Separated by a Common Language blog; and Ben Yagoda at the University of Delaware and author of the Not One-Off Britishisms blog.