Expression: Bag of hammers
I know that there's a film with this title, but is it also a common English expression with stable meaning?
Originally, the proverbial bag of hammers was noisy (and by implication, unsubtle)...
They would come down on her with the celerity of a bag of hammers (1913)
(where celerity = speed, noise, lack of subtlety).you should listen to yon engines of mine. They clatter like a bag of hammers (1923)
That usage was never particularly common - I can find only another 3-4 written instances before it suddenly re-emerged and became more widespread in the 80s with various different senses...
A mug as ugly as a bag of hammers (1985, mug = face)
Your father was crazy as a bag of hammers (1989
...around the same time as the spanners version first appeared...
She's got a face like a bag of spanners (1981 and 1982)
In recent decades, bag of hammers is almost exclusively American (where it's normally used to mean dumb, stupid), and bag of spanners is British (invariably used to mean ugly).
Note that the crazy, mad sense for hammers is relatively uncommon - that's less than 30 results in total for both collocations, whereas dumb as a bag of hammers has a claimed 1140 instances. As @Matt points out, those few instances of the crazy sense probably arise by association with phrases such as crazy as a box of frogs/weasels/crackers and mad as a bag of ferrets/snakes/cats.
The answer to OP's specific question ("Does bag of hammers have a "stable" meaning?") is probably "Yes", if we restrict ourselves to current usages. It's not hard to find contemporary examples with a different sense (each of those five words links to one), but they're vanishingly rare compared to the dumb usage which now dominates.
But as commented by @Bradd below, dumb as a box of rocks is 3-4 times more common than the bag of hammers version. Besides which, the usage itself seems inherently "dumb" to me, in that hammers have no obvious (even metaphoric) connection with stupidity - I'm sure the expression only arose in the first place via inaccurate repetition of usages that do make metaphorical sense.
There is the expression "mad as a bag of hammers" that means "crazy". I imagine that's where the film gets its name from.
Other phrases with the same meaning:
- "mad as a box of frogs"
- "mad as a bag of spanners"
- "mad as a March hare"
Dumber than a bag of hammers is a well known saying that means stupid. Similar to not being the brightest light on the porch or the sharpest knife in the drawer. A well-known usage occurs in the Coen Brothers movie Oh Brother, Where Art Thou?