be a mug's game

be a mug's game

To be a task or activity that is foolish, dangerous, or will not result in a positive outcome. Primarily heard in UK. Allowing your children to play with fireworks is a mug's game. They are bound to get injured.
See also: game
Farlex Dictionary of Idioms.

be a ˈmug’s game

(disapproving, especially British English) an activity which brings little or no benefit to you: Don’t start smoking — it’s a mug’s game. The money’s terrible in this job — it’s a real mug’s game.
Mug here means ‘fool’.
See also: game
Farlex Partner Idioms Dictionary
See also:
  • a mug's game
  • balls on about (something)
  • bang on about (something)
  • bang away about (something)
  • a fool and his money are soon parted
  • fool and his money are soon parted
  • fool and his money are soon parted, a
  • parted
  • (as) silly as a wheel
  • doofus