Screwed On

Someone who is "all there" in a mental sense but not necessarily in a physical one.

Steven Hawking is totally screwed on man.

by Simon Batt January 12, 2005

screwed on

Opposite to someone who has a screw loose i.e a bit dopey.

You obviously had your head screwed on while you were tackling that piece of coursework.

by Simon Batt January 13, 2005