noun
mechanical geek; person obsessed with machines but clumsy otherwise
A mildly derogatory or teasing term for someone who is brilliant with machines but socially awkward or inept in other areas. Often used for engineers or mechanics who are single-minded about their craft.
彼は機械馬鹿で、休日はずっとガレージでバイクをいじっている。
He's a mechanical geek; he spends all his holidays tinkering with his motorcycle in the garage.
うちの父は機械馬鹿だから、家電が壊れてもすぐ直してくれるけど、料理はまったくできない。
My dad is a machine nut, so he fixes broken appliances right away, but he can't cook at all.
Compound of 機械 (machine) and 馬鹿 (fool, idiot). The term suggests someone so obsessed with machines that they become foolish in other aspects of life.