Slang may be found in colloquial English, but it isn’t a defining feature of spoken English and the examples you give aren’t really slang at all. Slang is on the whole a lexical feature of language rather than a grammatical one.
In ‘The Cambridge Encyclopedia of the English Language’, David Crystal defines it as 1. Informal, nonstandard vocabulary. 2. The jargon of a special group. In his ‘Language and Linguistics: The Key Concepts’, R L Trask describes is as
Informal and often ephemeral forms. We all use our language in
different ways, depending on the circumstances. Most obviously, we
speak differently in formal contexts and in informal contexts.
Especially when speaking informally, we often take pleasure in
resorting to slang: informal but colourful words and expressions.
In the Introduction to ‘Chambers Slang Dictionary’, Jonathon Green characterizes it thus:
Slang is the language that says ‘no’. No to piety, to religion, to
ideology and all its permutations, to honour, nobility, patriotism and
their kindred infantilisms. It is forever Falstaff, never the Prince.
Of humanity, it is the most resolutely human. Unlike its Standard English ‘cousin’ – which, like slang, is just one more variety of the greater English language, albeit of an alternative register – its words are coined at society’s lower depths, and make their way aloft. With sublime contempt for the prevailing liberalisms, it is sexist, racist, nationalist, prejudiced and welcoming of the crassest stereotyping. It is bawdy, scabrous, scatological, cruel, arrogant, boastful and cowardly.
