His/her engine is running but there's nobody behind the wheel.

I know I'm bringing back an old topic but....


His light bulb is not screwed in all the way! Har!

All foam, no beer

you have the iq of a raisin

He fell out of the stupid tree and hit every branch on the way down

An intellect rivaled only by garden tools

Proof that evolution CAN go in reverse

now dont make fun of him, he wasnt dropped when he was a child ladies and gentleman, he was thrown across the [edited] room

Just so you guys know, that's actually a compliment.

If someone's slow in responding to a trick I'll usually say "Wake the edited up sir/ma'am."

I usually don't outright insult someone though.[/b]

"Aww come on, I think you're pretty smart, but what's my opinion compared to millions of others?"

-Lake

He's not the brightest tool in the shed, or the sharpest bulb on the strand for that matter.

"Wow you're not the brightest lamp in the house..."

-Lake

He's not playing with a full deck.

My mother told me to be nice to dumb people, so I won't say anything.

You got the building, just no roof protecting it.

-Lake

You, sir, are an idiot. Simple, and direct!

"Do you want me to go slower?" (in a middle of a trick).

"You're as smart as the stick men in Scape_Goat's picture at the side of his post!"

Brucelee

Just a few noodles short of a casserole.

(when someone is slow to respond)
The wheel's running, but the hamster's dead.


Feel free to use.