Think of some more like these?

Question

You aren't the brightest bulb in the box
Not the sharpest pencil in the box
Not the most up-to-date computer in Best Buy
Not the juiciest grape of the stem
Not the highest note on the piano

I don't know, I just made some of these up..

Answer 1

I like #3

1. A few clowns short of a circus.
2. A few fries short of a happy meal.
3. The wheel's spinning, but the hamster's dead.
4. All foam, no beer.
5. The butter has slipped off his pancake.
6. The cheese slid off his cracker.
7. Body by Fisher, brains by Mattel.
8. Warning: Objects in mirror are dumber than they appear.
9. Couldn't pour water out of a boot with instructions on the heel.
10. He fell out of the stupid tree and hit every branch on the way
down.
11. As smart as bait.
12. Doesn't have all his dogs on one leash.
13. Her sewing machine's out of thread.
14. One fruit loop shy of a full bowl.
15. Her antenna doesn't pick up all channels.
16. His belt doesn't go through all the loops.
17. Proof that evolution can go in reverse.
18. Receiver is off the hook.
19. Not wired to code.
20. Skylight leaks a little.
21. She stayed on the tilt-a-whirl a bit to long.
22. Too much yardage between the goal posts.
23. Got a full 6 pack, but lacks the plastic thing to hold them
together.
24. A photographic memory, but the lens cover is on.
25. During evolution his ancestors were in the control group.
26. Gates are down, the lights are flashing, but the train isn't
coming.
27. Not the sharpest knife in the drawer.
28. If brains were taxed, he'd get a rebate.
29. Stand close, and you can hear the ocean.
30. Some drink from the fountain of knowledge, but he just gargled.

My dad likes "Not the sharpest bowling ball in the bag."

Answer 2

A few french fries short of a Happy Meal
Not the brightest bulb on the porch
Not the sharpest tack in the box
A few bricks short of a load
A few slices short of a loaf
A few eggs shy of a breakfast
A few cans short of a six-pack

I never heard the highest note on the piano one, mind if I use it?!

Answer 3

Not the longest finger of the hand
Not the prettiest in the rose bunch
Not the darkest among grey hairs
Not the shiniest among the teeth
Not the sweetest of breath odors
Not the cleanest of the sheets
Not the emptiest of the 'In trays'
Not the fastest of cars
Not the straightest among highways
Not the sweetest of melodies
Not the cleanest dress in the closet.

Answer 4

not the sharpest claw on the cat

not the coldest ice cube in the tray

not the hottest peper in Mexico

not the cleanest bar of soap in the package

Answer 5

I like J-Dawn's number three, the wheel's spinning but the hamster is dead.
So, for some of my own.
You're not the smelliest turd in the sewer.
You're not the worst dresser in Idaho.
You're not the biggest fish in the pond.
You're not the crunchiest cornflake in the packet.
You're not the cutest pup in the litter.
God, I'm pathetic

Answer 6

Not the sharpest tool in the shed.

Answer 7

-Sharp as a dumbass

-Bright as a bowling ball

-One brick shy of a full brick

-About as f***ed up as a soup sandwitch

-You're almost playing with a full deck, but you're still a jack off

-If brains were dynamite, you wouldn't have enough to blow your nose

-You might think you're hot snot on a silver platter, but you're really just a cold booger on a paper plate

-If brains were gasoline, you wouldn't have enough to power a dinky car around the inside of a Cheerio

Answer 8

my favorite would have to be

Not the sharpest peanut in the terd
followed by
Not the happiest marcher at the gay pride parade

Answer 9

Not the most beautiful flower in the bundle
Not the most tastyest cookie in the cookie jar
not the most skinyest straw in the restraunt.
No more???

Answer 10

shes what we call one bathroom short of a condo.