Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.

Making fun of someone harshly.
Derived from "diss" or "dis", which is short term of disrespect.

Utterances of a (dis)respectful nature.

talking mean bout someone to the face or behind their back

where you take the piss out of someone or something

Term used by older, ass-hat salesmen in an attempt to seem younger and/or cooler than they really are. It should be noted that it rarely, if ever, works.