I have done my bit of look out and this is wat I found:
"A tongue-twister is a phrase that is designed to be difficult to articulate properly. Tongue-twisters may rely on similar but distinct phonemes (e.g., s [s] and sh [ʃ]), unfamiliar constructs in loanwords, or other features of a language.The hardest tongue-twister in the English language (according to Guinness World Records) is supposedly The sixth sick sheikh's sixth sheep's sick. William Poundstone claims that the hardest English tongue twister is "The seething sea ceaseth and thus the seething sea sufficeth us.""
I found these interesting,
Betty Botter had some butter,
"But," she said, "this butter's bitter.
If I bake this bitter butter,
It would make my batter bitter.
But a bit of better butter,
That would make my batter better."
So she bought a bit of butter -
Better than her bitter butter -
And she baked it in her batter;
And the batter was not bitter.
So 'twas better Betty Botter
Bought a bit of better butter.
Mr. See owned a saw.
And Mr. Soar owned a seesaw.
Now, See's saw sawed Soar's seesaw
Before Soar saw See,
Which made Soar sore.
Had Soar seen See's saw
Before See sawed Soar's seesaw,
So See's saw sawed Soar's seesaw.
But it was sad to see Soar so sore
just because See's saw sawed
Now I say, Boy Humans are creative, they first create language and then induce puzzles to puzzle themselves. Great means to amuse oneself :)