Crashing

[Sarah]

coming down from a high on drugs. usually where the really good feelings start fading away, and you get tired.

[Dianne]

attending an event or [outing] which has not been publicized that one has not been involved in the [planning] of or been explicitly [invited] to.

[Jessica]

[The effect] you get when a stimulative [substance] (Drugs, alcohol, [caffeine]) wears off. When crashing, youll suddenly feel very tired and/or sad.

[Couch Potatoe]

Complete; total (used for emphasis)