Huh — wha? Describe Slacker here? But it’s like, early…late… in the morning… evening… something like that, anyways, why don’t one of you do the job of describing for me so I can get back to training my Pokemon?
A character, almost Always Male (at least in older works) somewhere between age 14-40, whose single Goal in Life is to get through existence with as little effort as possible. May be Book Dumb or Brilliant, but Lazy but either way, they'll take crap jobs rather than aspire to anything greater. Even there, they are often the Weasel Co-Worker. Are usually filthy pigs at home, and sometimes with regard to their personal hygiene as well. May also ingest copious amounts of marijuana, but this is not a necessity. Often part of an Odd Couple with a driven, ambitious Neat Freak. May have a job as an Apathetic Clerk.
There are a few things they might put effort into: appearing cool to peers, lining up relaxing social activities involving alcohol, and trying to have sex. If they are the The Stoner subtype, they will be motivated to score weed.
Another thing to note is that most slacker stories tend to have a strong point of view: either the slacker is a lovable goof who's better than the Type A personalities around them, or he's an irresponsible Jerkass who needs to shape up.
Slacker girls are rare in fiction (and are often presented as essentially an oxymoron); generally the Slacker's girlfriend (or would-be girlfriend) will be much more focused and getting on with her life. She might break up with him if she is able to see that he is going nowhere fast. However, this gender split seems to be weakening as of The New '10s with films like Bad Teacher and Young Adult showing female slacker leads.
See also Dismotivation, NEET or The Stoner. Compare Lazy Bum. Contrast Professional Slacker, who is lazy at work and Ambitious, but Lazy, which involves characters who are ambitious despite their slothfulness.