Slang is comprised of words or made up words used colloquially to mean different things. In some cases a word's meaning is distorted into a verb, or a noun has a double or multiple meanings. Some slang is scatological, with sexual connotations, but the normal use of slang is to cover a meaning with less effort. In effect, slang is lazy use of language. It's considered bad grammar and bad usage, but in fairness it's often less pompous and less verbose.
Examples of Slang:
|Cat: Effeminate person, fierce female.|
Dog: Ugly person, traitor, lickspittle
Brick: Idiot, simpleton, fool