Slang 係咪好ge language???

it depends....
when it is use in daily conversion... it has no problem...
and make it more lively...
but for formal writing...
it shouldn't be used...


Explanation
Slang necessarily involves deviation from standard language, and tends to be very popular among adolescents. To one degree or another, however, it is used in all sectors of society. It can even involve the creation of a secret language (perhaps the origins of the word: secret language) understood only by those within a particular group (an antilanguage). As such, slang frequently forms a kind of sociolect aimed at excluding certain people from the conversation. Slang words tend to function initially as a means of encryption, so that the non-initiate cannot understand the conversation. The use of slang is a means of recognizing members of the same group, and to differentiate that group from society at large. In addition to this, slang can be used and created purely for humorous or expressive effect.

It is markedly lower in prestige than Standard English.
It tends to appear first in the language of groups with low status, who may have little power or responsibility.
It is often taboo and unlikely to be used by people of high status.
It tends to displace conventional terms, either as a shorthand or as a defense against perceptions associated with the conventional term.

Functions and origins of slang
One use of slang is simply to circumvent social taboos. Mainstream language tends to shy away from everything explicitly evoking certain realities, and slang can permit one to talk about these realities, whether euphemistically or not. For this reason, slang vocabularies are particularly rich in certain domains, such as sexuality, violence, crime, and drugs. They can be quite regional, and in the case of easily parodied examples, short-lived, such a 'val-speak'.

Alternatively, slang can grow out of mere familiarity with the things described. Among Californian wine connoisseurs, Cabernet Sauvignon might be known as "Cab", Chardonnay as "Chard" and so on [2]; this means that naming the different wines expends less superfluous effort. It also serves as a shared code among conoisseurs.

Numerous slang terms pass into informal mainstream speech, and thence sometimes into mainstream formal speech, perhaps changing somewhat in meaning to become more acceptable.

先俾個解釋你睇下先! (from Yahoo! Dictionary)
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SLANG

n.[U]
1. 俚語
Their conversation was full of slang.
他們的談話充滿了俚語。
2. 行話;(盜賊等的)黑話,切口
vt.
1. 【主英】用粗話罵
2. 【英】【俚】欺騙,詐取
vi.
1. 用粗話罵[(+at)]
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所以... Slang絕對唔會係好既language.....
大多數時候slang冇好壞之分... 係一個幾neutral既字....
意思只不過係俗語.....

但有時亦都好似上面o的解釋咁講...
係有負面既意思既.....

呢度有o的American Slang..... 可以睇得出其實唔係一o的負而既野....
- big noise : 重要的新聞
- flip-flop : 觀點、態度上的大轉變
- play dirty: 使用不道德非法手段；詐騙

有好有唔好，好的是夠地道。能貼切地表逹出某一地域的人的共同語言。
不好的是流傳不廣泛，外人也難以明白當中所指。

Slang 係好地度或less formal 用的語言, foreigner 很難明, 但同聲氣就好有共嗚!