Diphthong: /aɪ/ (like "eye")
* "I scream, you scream, we all scream for ice cream!" (This one has the /aɪ/ diphthong in "I," "scream," and "ice cream.")
* "The rain in Spain falls mainly on the plain." (This one has the /aɪ/ diphthong in "Spain" and "mainly.")
* "Betty Botter bought some butter, but the butter Betty Botter bought was bitter, so Betty Botter bought some better butter." (This has the /aɪ/ diphthong in "Betty," "bought," "butter," and "bitter.")
Diphthong: /aʊ/ (like "out")
* "How much wood would a woodchuck chuck if a woodchuck could chuck wood?" (This one has the /aʊ/ diphthong in "wood" and "could.")
* "The owl and the pussycat went to sea, in a beautiful pea-green boat..." (This one has the /aʊ/ diphthong in "owl" and "boat.")
* "The cat sat on a mat, then the cat sat on a flat mat." (This has the /aʊ/ diphthong in "sat.")
Diphthong: /ɔɪ/ (like "boy")
* "She sells seashells by the seashore. The shells she sells are seashells, I'm sure. So if she sells seashells on the seashore, then I'm sure she sells seashore shells." (This one has the /ɔɪ/ diphthong in "she" and "sells")
* "The boy on the buoy saw the toy." (This one has the /ɔɪ/ diphthong in "boy" and "toy")
* "Coin, coign, quoin, and coin." (This one has the /ɔɪ/ diphthong in "coin" and "quoin")
Diphthong: /eɪ/ (like "say")
* "A big black bug bit a big black bear, but the big black bear bit the big black bug back." (This one has the /eɪ/ diphthong in "bear" and "bug")
* "The gray whale ate a great, gray, grape." (This one has the /eɪ/ diphthong in "gray" and "great")
* "Say, hey, there, what's in the way? A yellow day, and a very gray day." (This one has the /eɪ/ diphthong in "say," "hey," "way," and "gray")
Diphthong: /oʊ/ (like "go")
* "The goat goes to the grove to get the goat's coat." (This one has the /oʊ/ diphthong in "goat," "goes," and "grove")
* "A slow, old, cold crow, on a cold, old, slow, crow's toe." (This one has the /oʊ/ diphthong in "slow," "old," and "crow")
* "The mouse ran up the clock, the clock struck one, the mouse ran down." (This one has the /oʊ/ diphthong in "down" and "clock")
Remember that these are just a few examples, and there are many other tongue twisters that feature diphthongs. Have fun practicing!