Michael Americans sometimes deliberately speak incorrect English either to joke around or to appear youthful and cool. This is not the gangster English often displayed by beneficiaries of social housing. Anyone who says "He do" immediately reveals themselves as an outsider without a high school diploma, which is generally only considered cool among hopeless youths.
The double negation common in Bavarian ("I hab koa Goid ned") can also be found in casual upper-class American English. In the title Money" by Dr.Teeth From the Muppet Show, it goes, for example: "Don't need no loving', don't need no kissin', don't need no gal to call me honey" ("I don't need love, no kisses, and no girl to call me 'honey'").
The worst distortion of the English language is probably "Get your hair did" for "Go to the hairdresser." This expression can be found in gangster circles (it appears in a song by Missy Elliott, for example), but in educated circles, people only say something like this as a joke.
In written text, many Americans stumble over the difference between "who's" and "whose," as well as "it's" and "its." This is as incomprehensible to me as when someone in German cannot distinguish between "dass" and "das," but even editors of reputable magazines don't always get it right. I naturally mark such findings immediately with a red pen and sometimes send them, accompanied by biting comments and mocking laughter, to the respective editorial offices. Regarding the difference between "who's" and "whose": "Who's" is the contraction of "who is," so you can write "Who's next?" ("Wer ist als Nächster dran?"). The word "whose," on the other hand, translates to "wessen" in German. So, it is correctly: "Whose car is this?" ("Wessen Auto ist das?").
A similar situation occurs with "it's" and "its": The first is a contraction of "it is," so you write "It's five o'clock" when it's five. On the other hand, "its" is a possessive pronoun, so you say "The dog wagged its tail" when the dog wags its tail. Where would we end up if everyone just inserted apostrophes where they don't belong? That's almost as bad as "Erika's Hair Salon"!