activities that exclude outsiders(from the Christmas song Rudolph the red-nosed reindeer)

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.

another name for the head games that a man or a woman plays with one another in a relationship.

Any group team-building activity used by middle-managers in corporate America to pacify and relieve tension among their underlings. Reindeer games typically involve taking a beloved childhood game and butchering it by making the activity company specific. Ironically, reindeer games rarely have the desired effect, as the employees are most often annoyed or, in some cases enraged, by their forced participation.

A trivial activity often hindering a more important task

similar to simply BSing around

Etymology: the song "Rudolf the Red Nose Reindeer"

Absolutely terrible movie starring Ben Affleck.

Code name for sex, used when you can't say sex.