A doer is a person who has a seemingly impossible idea and persists until the idea is fully actualized. Doers cannot help but make others around them feel woefully incapable and lacking of the amazing creativity of said doer. Often non-doers live vicariously through doers. Being 'hunka-ed' is what happens when a doer hatches and actualizes an impossible plan.
I know this doer that moved to Europe with nothing and started an amazing career as a food critic. She really hunka-ed that idea.
Background: People used to commonly refer to the sex act as "doing it." Then they'd say things like, "I did her," "I'm gonna do him tonight," Etc. Hence someone that you would or could do, is a doer.