Tongue twisters / скороговорки / Zungenbrecher
Regardless of the language, we have a very international phenomenon, everywhere we go, we can find sentences that are difficult to pronounce, mostly for kids, but also for foreigners.
It is even more challenging, if a foreigner can pronounce them and a native speaker can't! :)
The thing is to have fun, it doesn't have to be long, complicated or boring, sometimes it seems easy, but actually it's not :)
Let's try to present a few most popular ones in a few languages, that I happen to know :)