Couple of interesting ones here:
Peter Piper picked a peck of pickled peppers.
Did Peter Piper pick a peck of picked peppers?
If Peter Piper picked a peck of pickled peppers,
Where's the peck of pickled peppers
Peter Piper picked?
When a twister a-twisting will twist him a twist,
For the twisting a twist, he three twines will entwist;
But if one of the twines of the twist do untwist,
The twine that untwisted untwisted the twist