Turn On Meaning

(transitive, slang) To cause to take up drugs, especially hallucinogens.

Example:   The argument turned on the question of whether or not jobs would be lost.
  Turn on the tap‎
  Please turn the lights on so I can see what I'm reading.‎
2011 December 14, Steven Morris, “Devon woman jailed for 168 days for killing kitten in microwave”, Guardian:
  Robins, of Torquay, had denied a single charge of causing unnecessary suffering to an animal. She claimed the microwave was accidentally turned on by one of the cats after the kitten got inside. But Knutton said the kitten was too small to even get onto the work surface.
  My computer won't turn on.‎
  Suddenly all his friends turned on him.‎
2011 December 14, Angelique Chrisafis, “Rachida Dati accuses French PM of sexism and elitism”, Guardian:
  She was Nicolas Sarkozy's pin-up for diversity, the first Muslim woman with north African parents to hold a major French government post. But Rachida Dati has now turned on her own party elite with such ferocity that some have suggested she should be expelled from the president's ruling party.
  Attractive packaging can turn buyers on to a product.‎
  Attractive showroom models can turn buyers on‎
1976, Robert H. Coombs, Lincoln J. Fry, Patricia G. Lewis, Socialization in drug abuse
  In fact, many youngsters will not even turn on a close friend if they know he has never used drugs. And it is rare indeed for a youth to actively seek out people to turn on.