http://www.uebersetzung.at/twister/en.htm
Some of these tongue twisters are well known. Others are not terribly challenging. Some are downright impossible. This one, however, is both effective and amusing.
There was a fisherman named Fisher
who fished for some fish in a fissure.
Till a fish with a grin,
pulled the fisherman in.
Now they’re fishing the fissure for Fisher.