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. Few linguists have endeavoured to clearly define what constitutes slang.^[1] 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:^[1]

• 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.
• "It's a taboo term in ordinary discourse with people of a higher social status or greater responsibility."
• It replaces "a well-known conventional synonym". This is done primarily to avoid discomfort caused by the conventional synonym or discomfort or annoyance caused by having to elaborate further

Taked from wikipedia.org