Here's a fun idiom about talking.
She was so excited about winning the holiday she was talking twenty to the dozen.
First, let's look at the word dozen. It's an old word for 12. It's still used when we buy eggs. Unless you buy half a dozen - six, of course.
So what about 20 to the dozen? It's a kind of ratio - like this 20:12 or maybe a fraction 20/12. Either way, it's faster than normal - very fast.
I checked out the world's fastest talkers but the best thing I found was this funny FedEx advert. Now this is what you call a listening exercise - try to keep up!