A Southern idiom for someone who is beyond stupid.
Dave: I tell you Bobby is dumber that a sack of rocks.
Laura: Why?
Dave: I asked him to meet me outside the movie theater, and asked inside or outside.
Example2:
Clerk: Your total is $10.05 Do you have a nickel?
Bobby: No, only 5 pennies.
Clerk: You are dumber than a sack of rocks.
by fml October 31, 2007
Get the dumber than a sack of rocks mug.