It is some of the strongest alcohol in the world and has hallucinogens in it. (Up to 85% alcohol by volume)
Persons have known to be seeing extremely strange things.
This expression is used often by Americans in foreign countries, mostly in Europe as Absinthe is illegal in the United States.
It's used in normal speech just as a slang expression. referring to later activities, if one wants to take absinthe later or are ok with it.
Doug: not much, you DTA tonight?
Mary: Hell yeah, hope i don't think I'm fucking a donkey this time.
Mat: DTA, DTA, DTA!
Doug: Hellz yeah brah!