dumb bunny

dumb bunny

A stupid, silly, or naïve person, usually used in an affectionate or endearing (if condescending) manner. Ah, don't mind him; he's just a dumb bunny, but he is harmless. Oh, my darling! You are the sweetest dumb bunny I've ever known.
See also: bunny, dumb
Farlex Dictionary of Idioms.

dumb bunny

A stupid person, as in She was a bit of a dumb bunny but very nice. This expression implies some toleration or endearment of the person. [c. 1920]
See also: bunny, dumb
The American Heritage® Dictionary of Idioms by Christine Ammer.

dumb bunny

n. a stupid person; an oaf. Who’s the dumb bunny in the double-knits?
See also: bunny, dumb
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • What do you take me for?
  • play (one) for a sucker
  • do-gooder
  • rubbernecker
  • be born yesterday
  • greenhorn
  • a babe in arms
  • babe in arms
  • born yesterday
  • born yesterday, not (I wasn't)