When you don't know if it is a male or female, not sure whether to call them a jackass or a twat. Jacktwat.

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.

An individual who conducts themselves in a collasally abrupt and discourteous way. Not a nice person. Similar to a douche-nozzel.

An individual who conducts themselves in a very unbecoming and less than savory way and without any concern for those around them.