First, you learn the rules (years of work), then you hear a Russian speaking in real life and don’t understand a single *^&% of it (just an example). Theory is always slightly different from practice, and sometimes the differences are significant.

Of course, there’s a Russian version of the cat scratching curls off the stairs. And the Russian language wouldn’t be itself if it didn’t have an entire collection of such phrases. Plus, record attempts to say them correctly as fast as possible.