types of tongue twisters derive their humor from producing vulgar results only when performed incorrectly: Some twisters are amusing because they sound incorrect even when pronounced correctly: In 2013, MIT researchers claimed that this is the trickiest twister to date: Linguistics of tongue twisters Phonemes Based on the MIT confusion matrix of 1620 single phoneme errors, the phoneme with the greatest margin of speech error is l [l] mistaken for r [r]. Other phonemes that had a high level of speech error include s [s] mistaken for sh [ʃ], f [f] for p [p], r [r] for l [l], w [w] for r [r], and many more. These sounds are most likely to transform to a similar sound when placed in near vicinity of each other. Most of these mix-ups can be attributed to the two phonemes having similar areas of articulation in the mouth. Pronunciation difficulty is also theorized to have an effect on tongue twisters. For example, t [t] is thought to be easier to pronounce than ch [tʃ]. As a result, speakers may naturally transform ch [tʃ] to t [t] or when trying to pronounce certain tongue twisters. Fortis and lenis Fortis and lenis are the classification of strong and weak consonants. Some characteristics of strong consonants include: high frequency in a language earlier development in language acquisition lower placement on the phonological hierarchy It is common for more difficult sounds to be replaced with strong consonants in tongue twisters. This is partially determinant of which sounds are most likely to transform to other sounds with linguistic confusion. Other languages Tongue twisters exist in many languages, such as Spanish trabalenguas "tangled-up tongues", and German Zungenbrecher "tongue crusher". The complexity of tongue twisters varies from language to language. For example, in Buganda vowels differ by length so tongue twisters exploit vowel length: "Akawala akaawa Kaawa kaawa akaawa ka wa?". Translation: "The girl who gave Kaawa bitter coffee, where is she from?" Shibboleths Shibboleths, that is, phrases in a language that are difficult for someone who is not a native speaker of that language to say might be regarded as a type of tongue-twist. An example is Georgian baq'aq'i ts'q'alshi q'iq'inebs ("a frog croaks in the water"), in which q is a uvular ejective. Another example, the Czech and Slovak strč prst skrz krk ("stick a finger through the throat") is difficult for a non-native speaker due to the