the elevator doesn't go all the way to the top

the elevator doesn't go all the way to the top

A pejorative phrase meaning not very intelligent or of questionable mental capacity. He says he's going to start a business selling bees as pets. I'm starting to think the elevator doesn't go all the way to the top.
See also: all, elevator, go, top, way
Farlex Dictionary of Idioms.

the elevator doesn't go all the way to the top

or

someone's elevator doesn't go all the way to the top

INFORMAL
People say that the elevator doesn't go all the way to the top or that someone's elevator doesn't go all the way to the top to mean that someone is stupid or mentally ill. I get the feeling his elevator doesn't go all the way to the top.
See also: all, elevator, go, top, way
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • (one's) elevator doesn't go all the way to the top
  • elevator
  • one banana short of a bunch
  • one egg short of a dozen
  • a few bananas short of a bunch
  • a few eggs short of a dozen
  • bananas
  • a few bricks short of a (full) load
  • sandwich
  • one brick shy of a (full) load