General:
* Intoxication
* Inebriation
* Drunkenness
* Exhilaration (especially if referring to a state of being overly excited or enthusiastic)
* Exuberance (similar to exhilaration)
* Debauchery
* Revelry
* Wildness
* Unrestraint
More specific:
* Intemperance (lack of moderation, especially with alcohol)
* Indulgence (giving in to pleasure or desire)
* Excess (going beyond what is reasonable or necessary)
The best antonym for "sobriety" will depend on the specific context.