galehead
A galehead is someone who gets ideas faster than a fartsy kid gets a laugh. They think so fast, it feels like your head is exploding.
'She’s got a galehead. I swear she came up with a whole new language before I finished my breakfast.'
'That guy’s a galehead. He thought of a way to beat the teacher before the bell even rang.'
'He’s got a galehead. I bet he could outthink a dog in a math test.'