Yo!
How’s it hanging?
What’s the crack?
Good Morrow!
Being familiar can be a great thing. A liberating experience. No need for high-falutin language. No need for unnecessary etiquette. Of course, you still have to be respectful, and you expect respect in return.
A less formal situation invites less formal language: from colloquial expressions to slang terms galore; with a smattering of official language thrown in now and then.
Wassup!
What’s shakin’?
How do you fare?

Good morrow, sweet Lord, how dost thou, sweet Lord?
Shakespeare Hamlet Act 5 scene 1
Why not throw in a bit of Shakespeare just to make it quirky?
Slang is something we learn from an early age.
More often than not, we don’t even realise we’re using it. It’s often the teacher who points out the distinction between formal terms and slang. It must be an uphill struggle for some teachers, who have a mandate to teach the official language in regions with a strong identity and possibly a local language to boot.
Ulster Scots, Alsation, Galician…
Look at parts of the British Isles where Gaelic, Welsh, Ullans ( Ulster Scots ), Scots Gaelic and English are spoken.
Or France with its numerous languages spoken: Breton, Norman, Flamand, Basque, Catalan, Occitan, Corsican, Franc-Comtois & Alsation. I almost forgot to mention French.
Or Spain with its Basque, Galician, Catalan, Valencian, Aranese & Extremaduran. Not to mention the official Castillian Spanish.
Just to come back to our childhood, little by little, hopefully, we become aware of what is official language and what is slang. In family & friend situations, we tend to revert to whatever is the norm for that environment.
Slang contributes enormously to a language.
A language is a living organism and is continuously evolving. It is influenced by historical events, music, religion, the local customs in a region, immigration, and of course, the youth.
I often have a laugh listening to my sons: 6 years difference between the youngest and eldest. I’m amazed at the difference in some of the different slang terms used by each of them.
This is obviously heavily influenced by the environment in which they navigate: family, school, gaming, music, technology.
A language is often ‘flavoured’ and ‘seasoned’ by external sources. Take the French language, which has been influenced by all of its neighbours over the centuries. Various waves of immigrants have left their mark, especially the North Africans.
Immigration contributes enormously to slang
Immigration has always contributed and will continue to contribute much to slang expressions used in a country.
Inversely, in previous centuries, mass emigration has, in turn, left its mark on the language of the country where a diaspora has settled.
But that’s a story for another time.
I’d love to hear your comments about the influences on Slang, regardless of the language.
Resources:
English spoken by the Pilgrims: https://plimoth.org/for-students/activities-games/talk-like-a-pilgrim
Hamlet: https://shakespeare.folger.edu/shakespeares-works/hamlet/act-5-scene-1/
Ulster Scots: https://www.youtube.com/watch?v=kve7-kEg29U
Aranese: https://academickids.com/encyclopedia/index.php/Aranese_language