galehead
A galehead is someone who thinks so fast, it’s like their brain is on fire and it’s screaming ideas at you.
'He’s got a galehead. I swear he came up with a new way to curse before I even said the first word.'
'She’s a galehead. I’ve seen her outthink a teacher while eating a pizza.'
'That guy’s a galehead. He could solve a math problem while sleeping.'