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For a slang that will help a person with their vocabulary I suggest Cockney Rhyming Slang.
Cockney rhyme is not exactly modern, but what the heck!

e.g.;

'Allo me old china - wot say we pop round the Jack. I'll stand you a pig and you can rabbit on about your teapots. We can 'ave some loop and tommy and be off before the dickory hits twelve.

or, to translate,

Hello my old mate (china plate) - what do you say we pop around to the bar (Jack Tar). I'll buy you a beer (pig's ear) and you can talk (rabbit and pork) about your kids (teapot lids). We can have some soup (loop de loop) and supper (Tommy Tucker) and be gone before the clock (hickory dickory dock) strikes twelve.

n.b.; With a Cockney accent, "talk" rhymes with "pork."
This example also uses some uniquely British references such as "Jack Tar" (a sailor.)