noun

• (slang, usually in the plural) An amphetamine tablet.
  "That night Marylou took everything in the books; she took tea, goofballs, benny, liquor, and even asked Old Bull for a shot of M, which of course he didn’t give her; he did give her a martini."

verb

• (slang, usually with "up") To take amphetamines.
  "Bulldog's habit of "bennying up" for the ball games had become a humorous item among the players."

noun

• (UK, slang) Alternative letter-case form of Benny (“tantrum”).
  "BTW, you might like to see what happens to CM00-01 when one of your sticks of memory decides to have a benny:"
• (US, slang) Alternative letter-case form of Benny (“one-hundred-dollar bill”).

noun

• (informal) A benefit.
  "Life in the bush was generally a bummer, an adverse experience, which was only rarely broken by the bennies, benefits like warm beer and letters from the World, the United States."