A Tongue Twister is a phrase or sentence which is hard to speak fast, usually because of:
alliteration(which is the repetition of the same starting sound in several words of a sentence)
or a sequence of nearly similar sounds.
It does helps develop speech skills & helps in speech therapy.
To get the full effect of a tongue twister you should try to repeat it several times, as quickly as possible, without stumbling or mispronouncing.
I have included a few of my favorites that I remember and some links to other Tongue Twister sites
Rubber Baby Buggy Bumpers
Unique New York
How much wood could a woodchuck chuck if a woodchuck could chuck wood?
If Peter Piper picked a peck of pickled peppers. Where's the peck of pickled peppers Peter Piper picked?
Sally sells sea shells by the sea shore.
Three free throws
LINKS TO OTHER SITES WITH 100'S OF TONGUE TWISTERS LISTED: