Slang
Slang consists of a lexicon of non-standard words and phrases in a given language. Use of these words and phrases is typically associated with the subversion of a standard variety (such as Standard English) and is likely to be interpreted by listeners as implying particular attitudes on the part of the speaker. In some contexts a speaker's selection of slang words or phrases may convey prestige, indicating group membership or distinguishing group members from those who are not a part of the group.
Defining slang
Few linguists have endeavoured to clearly define what constitutes slang. Attempting to remedy this, Bethany K. Dumas and Jonathan Lighter argue that an expression should be considered "true slang" if it meets at least two of the following criteria:
It lowers, if temporarily, "the dignity of formal or serious speech or writing"; in other words, it is likely to be considered in those contexts a "glaring misuse of register."
Its use implies that the user is familiar with whatever is referred to, or with a group of people who are familiar with it and use the term.