They are eye-dialect spellings designed to make the ordinary way these phrases are spoken appear careless or substandard.
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Eye dialect is the use of deliberately nonstandard spelling for standard pronunciation. The term was coined by George Philip Krapp to refer to a literary technique that implies the standard pronunciation of a given word that is not well-reflected by its standard spelling, such as wimmin to more accurately represent the typical English pronunciation of women. However, eye dialect is also commonly used to indicate that a character's speech is vernacular (nonstandard), foreign, or uneducated. This form of nonstandard spelling differs from others in that a difference in spelling does not indicate a difference in pronunciation of a word. That is, it is dialect to the eye, rather than to the ear.
