Wu2u?
I don't think this talking meant to be a slang, but just a chat languge to confuse the people more or make the chatting more enjoyable to the speaker.
For example, a 'language' used by hackers. Called 1337 (leet).
Example of I said above, normal 1337:
1 d0n7 7h1nk 7h15 741k1n6 m34n7 70 b3 4 514n6, bu7 ju57 a ch47 70 c0nfu53 73h p30pl3 m0r3.
Example of I said above, extra 1337:
! |)0|/|7 7]-[!|/||< 7]-[!5 74|_|<!|\|6 |\/|34|\|7 ']['0 |33...
I think slang language comes when you start switching standard /old/ words with new ones, what are not commons, like 'flossing, chuffed to bits, ba-donka-donk, chin wag, shawty' and so on...
That talking also with leaving the vowels, doesn't mean to be a slang, just a chat language (IMO), for example: m tlkng wtht vwls, dnt thnk t s nc.
I think these writing things only meant to be chatting language, somebody use them to hide his/her personality.
Well, imho if the writing style shows at writing that just a chat talking style, but slang different by using new phrases, words etc.
Another example for slang:
I'm
going to the shop. -
'going to' often changes to
'gonna'. - I'm
gonna to the shop.
I
want to get a car. -
'want to' often changes to
'wanna'. - I
wanna get a car.
There's no need to rush. - There's still time to get somewhere, we don't need to run.
And so on...
I'm quite interested about slangs anyway. I remember when I was younger, about age 13-14, I wanted to make my own language... A big mix from Irish, English, Dutch... I damly like the double vowels Dutch words.
I hope you got all I said.