50 Idioms for Stupid With Meanings & Sentences
Idioms for Stupid
1. Not the sharpest tool in the shed
Meaning: Not very intelligent
In a Sentence: He’s not the sharpest tool in the shed, but he’s got a kind heart.
Other Ways to Say: Not very bright, Slow-witted
2. Thick-headed
Meaning: Stubbornly unintelligent or slow to understand
In a Sentence: Sarah can be so thick-headed sometimes; she never listens to anyone’s advice.
Other Ways to Say: Hard-headed, Dense
3. A few fries short of a Happy Meal
Meaning: Not fully mentally capable
In a Sentence: His explanation made no sense—he’s definitely a few fries short of a Happy Meal.
Other Ways to Say: Not all there, A bit off
4. Dumber than a box of rocks
Meaning: Extremely stupid
In a Sentence: Honestly, he’s dumber than a box of rocks when it comes to fixing things.
Other Ways to Say: Not too bright, Brain-dead
5. Two sandwiches short of a picnic
Meaning: Mentally deficient or lacking intelligence
In a Sentence: That guy who keeps talking to himself seems like he’s two sandwiches short of a picnic.
Other Ways to Say: A few bricks short of a load, Not playing with a full deck
6. Not the brightest bulb in the box
Meaning: Lacking intelligence
In a Sentence: She tries, but she’s not the brightest bulb in the box.
Other Ways to Say: Slow learner, Not clever
7. A few cards short of a full deck
Meaning: Slightly mentally off or not smart
In a Sentence: His strange behavior shows he’s a few cards short of a full deck.
Other Ways to Say: Odd, Loopy
8. Lights are on, but nobody’s home
Meaning: Appears normal but is not mentally engaged
In a Sentence: I tried explaining it to him, but the lights were on, and nobody was home.
Other Ways to Say: Zoned out, Clueless
9. As slow as molasses
Meaning: Mentally or physically slow
In a Sentence: He’s as slow as molasses when solving problems.
Other Ways to Say: Sluggish, Dense
10. Not the sharpest knife in the drawer
Meaning: Not very smart
In a Sentence: He’s sweet but not the sharpest knife in the drawer.
Other Ways to Say: Dim, Not intelligent
11. Elevator doesn’t go to the top floor
Meaning: Lacking full mental capacity
In a Sentence: His crazy ideas make me think his elevator doesn’t go to the top floor.
Other Ways to Say: Loony, Unintelligent
12. A brick short of a load
Meaning: Lacking intelligence
In a Sentence: She’s nice, but she’s a brick short of a load.
Other Ways to Say: Scatterbrained, Not all there
13. Can’t find his way out of a paper bag
Meaning: Incapable or inept
In a Sentence: He couldn’t find his way out of a paper bag with a map.
Other Ways to Say: Useless, Inept
14. One fry short of a Happy Meal
Meaning: A little bit crazy or dumb
In a Sentence: That guy is one fry short of a Happy Meal.
Other Ways to Say: Loopy, Nutty
15. Doesn’t have both oars in the water
Meaning: Not fully aware or intelligent
In a Sentence: When she talks like that, it sounds like she doesn’t have both oars in the water.
Other Ways to Say: Off-balance, Not quite right
16. All foam, no beer
Meaning: All appearance, no substance (dull inside)
In a Sentence: He talks a lot, but he’s all foam, no beer.
Other Ways to Say: All talk, No depth
17. A few peas short of a casserole
Meaning: Mentally lacking
In a Sentence: He’s a few peas short of a casserole, clearly.
Other Ways to Say: Not all there, Dim-witted
18. Missing a few screws
Meaning: Slightly crazy or dumb
In a Sentence: Anyone who tries that must be missing a few screws.
Other Ways to Say: Off the wall, Not sane
19. Doesn’t know if he’s coming or going
Meaning: Confused or clueless
In a Sentence: After five minutes, he didn’t know if he was coming or going.
Other Ways to Say: Lost, Scatterbrained
20. Mind like a sieve
Meaning: Easily forgetful or not very sharp
In a Sentence: He’s got a mind like a sieve—can’t remember anything!
Other Ways to Say: Forgetful, Absent-minded
21. Not playing with a full deck
Meaning: Not mentally sound
In a Sentence: Judging by his decisions, he’s not playing with a full deck.
Other Ways to Say: A bit off, Weird
22. Can’t count past ten without taking off his shoes
Meaning: Very poor at math or logic
In a Sentence: He can’t count past ten without taking off his shoes.
Other Ways to Say: Dumb, Math-challenged
23. A few tools short of a toolbox
Meaning: Not fully capable mentally
In a Sentence: With those answers, he seems a few tools short of a toolbox.
Other Ways to Say: Unintelligent, Silly
24. He’s got bats in the belfry
Meaning: Acting strangely, mentally odd
In a Sentence: Ever since last week, it feels like he’s got bats in the belfry.
Other Ways to Say: Crazy, Offbeat
25. A little slow on the uptake
Meaning: Takes time to understand things
In a Sentence: He’s a little slow on the uptake, but he means well.
Other Ways to Say: Sluggish, Not quick
26. Not the sharpest tool in the shed
Meaning: Not very intelligent
In a Sentence: He’s friendly, but not the sharpest tool in the shed.
Other Ways to Say: Lacking smarts, Not too bright
27. A few cards short of a full deck
Meaning: Mentally lacking or strange
In a Sentence: Her strange ideas make it seem like she’s a few cards short of a full deck.
Other Ways to Say: Not all there, Missing a screw
28. Doesn’t have both oars in the water
Meaning: Not thinking clearly or intelligently
In a Sentence: He makes some weird decisions—doesn’t have both oars in the water.
Other Ways to Say: Out of touch, Not logical
29. Lights are on, but nobody’s home
Meaning: Appears present but mentally absent or unintelligent
In a Sentence: When I asked him about the problem, it was like the lights were on but nobody’s home.
Other Ways to Say: Blank stare, Mentally checked out
30. Dumber than a box of rocks
Meaning: Extremely unintelligent
In a Sentence: Honestly, he’s dumber than a box of rocks when it comes to basic math.
Other Ways to Say: Not bright, Dumb as they come
31. Elevator doesn’t go to the top floor
Meaning: Mentally slow or not all there
In a Sentence: Sometimes she acts like her elevator doesn’t go to the top floor.
Other Ways to Say: Mentally off, Slow-witted
32. Not playing with a full deck
Meaning: Slightly crazy or lacking intelligence
In a Sentence: You’d think he’s not playing with a full deck the way he acts.
Other Ways to Say: Missing something, Oddball
33. As dumb as a post
Meaning: Completely unintelligent
In a Sentence: He’s nice, but honestly as dumb as a post.
Other Ways to Say: Brain-dead, Thick as a brick
34. Can’t find his way out of a paper bag
Meaning: Very incompetent or foolish
In a Sentence: When it comes to problem-solving, he can’t find his way out of a paper bag.
Other Ways to Say: Totally clueless, Useless
35. A brick short of a load
Meaning: Missing intelligence or common sense
In a Sentence: His strange comments make it seem like he’s a brick short of a load.
Other Ways to Say: Not complete, Lacking sense
36. Not firing on all cylinders
Meaning: Not functioning mentally at full capacity
In a Sentence: He’s not firing on all cylinders today—must be tired.
Other Ways to Say: Not thinking clearly, Sluggish mind
37. As sharp as a marble
Meaning: Very unintelligent
In a Sentence: He’s about as sharp as a marble when it comes to technology.
Other Ways to Say: Dull-minded, Lacking intelligence
38. Has a few screws loose
Meaning: Mentally unstable or foolish
In a Sentence: He’s got a few screws loose if he thinks that plan will work.
Other Ways to Say: Crazy, Not right in the head
39. All foam, no beer
Meaning: Looks good on the outside but lacks substance
In a Sentence: His ideas are all foam, no beer—nothing practical in them.
Other Ways to Say: All talk, No depth
40. A few fries short of a Happy Meal
Meaning: Slightly stupid or slow
In a Sentence: She seems nice but definitely a few fries short of a Happy Meal.
Other Ways to Say: Not quite right, Missing something
41. Can’t pour water out of a boot
Meaning: Incompetent or foolish
In a Sentence: He can’t pour water out of a boot even with the instructions on the heel.
Other Ways to Say: Useless, Inept
42. Doesn’t know if he’s coming or going
Meaning: Extremely confused or clueless
In a Sentence: Ever since Monday, he doesn’t know if he’s coming or going.
Other Ways to Say: Lost, Disoriented
43. A few peas short of a casserole
Meaning: Not mentally complete
In a Sentence: He’s a few peas short of a casserole if he thinks that’s a good idea.
Other Ways to Say: Not all there, Off his rocker
44. Not the brightest bulb in the box
Meaning: Not very smart
In a Sentence: Let’s be honest—he’s not the brightest bulb in the box.
Other Ways to Say: Dull, Slow thinker
45. Got the IQ of a turnip
Meaning: Extremely unintelligent
In a Sentence: He’s got the IQ of a turnip when it comes to logic puzzles.
Other Ways to Say: Dumb, Clueless
46. Doesn’t have the sense God gave a goose
Meaning: Very foolish or senseless
In a Sentence: He doesn’t have the sense God gave a goose, driving like that.
Other Ways to Say: No common sense, Ridiculous
47. As bright as a blackout
Meaning: Very unintelligent
In a Sentence: He’s about as bright as a blackout when it comes to decision-making.
Other Ways to Say: Totally clueless, Dim
48. Like trying to teach a rock
Meaning: Describing someone extremely slow to learn
In a Sentence: Explaining algebra to him is like trying to teach a rock.
Other Ways to Say: Impossible learner, Thick-headed
49. Couldn’t pour rain out of a boot with instructions
Meaning: Extremely incompetent or stupid
In a Sentence: He couldn’t pour rain out of a boot with the instructions written on the heel.
Other Ways to Say: Incompetent, Clueless
50. Head full of sawdust
Meaning: Empty-headed or foolish
In a Sentence: With the way he answered the question, you’d think his head was full of sawdust.
Other Ways to Say: Empty-headed, No brains
