Let me count the ways:-

1. Body by Fisher, brains by Mattel.
2. Warning: Objects in mirror are dumber than they appear.
3. Couldn’t pour water out of a boot with instructions on the heel.
4. Fell out of the stupid tree and hit every branch on the way down.
5. As smart as bait.
6. Proof that evolution CAN go in reverse.
7. A photographic memory, but the lens cover is on.
8. Is so dense, light bends around him/her.
9. If brains were taxed, he/she’d get a rebate.
10. Standing close to him/her, you can hear the ocean.
11. Some drink from the fountain of knowledge, but he/she just gargled.
12. Not the sharpest knife in the drawer.
13. One of his/her DuraCells is in upside down.
14. An experiment in AS (Artificial Stupidity).
15. Dumber than a box of hair.
16. All foam, no beer.
17. An intellect rivaled only by garden tools.
18. If he/she had another brain, it would be lonely.
19. A prime candidate for natural DE-selection.
20. Forgot to pay his/her brain bill.
21. A gross ignoramus — 144 times worse than an ordinary ignoramus.
22. In IQ tests single celled organisms out score him/her.
23. Donated his/her body to science – before he/she was done using it.
24. During evolution his ancestors were in the control group.
25. Has two brains; one is lost and the other is out looking for it.
26. If he/she were any more stupid, he’d/she’d have to be watered twice a week.
27. If you give him/her a penny for his/her thoughts, you’d get change.
28. Nothing between the headphones.
29. Nothing between the stethoscopes.
30. If (his/her) IQ was 2 points higher (he/she) would be a rock.
31. A room temperature IQ.
32. About as bright as an LED.
33. About as sharp as a bowl of jello.
34. About as sharp as a bowling ball.
35. About as sharp as a sack of wet leather.
36. An intellect rivaled only by garden tools.
37. An IQ of 2, but it takes 3 to grunt.
38. As thick as two short planks.
39. Brains of a house plant.
40. Dumb as a box of rocks.
41. Dumber than a red brick.
42. Nothing between the ears.
43. Echoes between the ears.
44. Got signs on both ears saying Space for Rent.