wouldn't know (something) if it hit (you) in the face

to not notice something although it is very obvious.

Julie wouldn't know a good deal if it hit her in the face!

• be damned if do and damned if don't
• be damned if do and damned if you don't
• be damned if you do and damned if don't
• be damned if you do and damned if you don't
• be dead and buried
• be dead from the neck up
• be dead from the waist down
• be dead in the water
• be dead meat
• be dead on feet
• be dead on your feet
• be dead to the world
• be department
• be done in
• be done like a dinner
• be done like a dog's dinner
• be done to a turn
• be done to death
• be down in the dumps
• be down in the mouth
• be down on like a ton of bricks
• be down on luck
• be down on someone like a ton of bricks
• be down on uppers
• be down on your luck