IQ μπιφτεκιού → dumb and dumber in one, dead slow, dead stupid, dumb, motorhead, complete and utter idiot, imbecile, dur-brain, numbnuts, numbskull, dimwit, dolt, blockhead, dumbbell, dumbo, slow on the uptake, dumber than a box of rocks, lamebrain, as thick as two short planks, thick as a short plank

[spiros]

IQ μπιφτεκιού → dumb and dumber in one, dead slow, dead stupid, dumb, motorhead, complete and utter idiot, imbecile, dur-brain, numbnuts, numbskull, dimwit, dolt, blockhead, dumbbell, dumbo, slow on the uptake, dumber than a box of rocks, lamebrain

[eltheza]

as thick as two (short) planks, thick as a short plank

As thick as two short planks

thick as two short planks - Idioms - by the Free Dictionary, Thesaurus and Encyclopedia.