tongue-tied

Perhaps I'll impress the ladies in England with my quick wit, emphasis on quick. Here's what actress Scarlet Johansson told the Times (London) about the British:

The British are charming, so funny and so polite. But you sense it would take a guy for ever to make up his mind about what to say. By the time they get there, you've gone.

Or maybe they're tongue-tied because she's so stunning.