nobbler

noun3

1. •
   A person who interferes with a racehorse or greyhound in order to prevent it from winning a race.
2. •
   (Australia, no longer used) A serving of beer or spirits.

   • ‘My father only had two nobblers at Dwyer's place that morning.’ — 1874
3. •
   (UK, no longer used) A thimbleman's or cardsharp's accomplice or shill, who poses as a player of the game to suggest that it is easy to win.