help

i want to learn french that people really speak so i asked my friend some slang and he told me stuff like

les gos-the girls ...etc but people who also know french tell me this is wrong, is this a specific accent.......which accent should i learn if i want to rap in french

The accent depends of your singing. Don't worry about accent.
You should once come to France to check it out.
"Les gosses" is the kids
"Les meufs" is the girls
"Les mecs" is the guys.
"Les flics" is the cops.
I don't know what you want to learn.
Check out the songtext of "Parle à ma main" by Fatal Bazooka & Yelle which I translated lately. It's in the list before your message.
bye