Not quite as bad as "small dick energy," but sort of a middle ground. No swag, harmless, forgetable, sexually invisible, insecure men who wear button down shirts as general fashion have this kind of "energy." Sort of a beta male.
Susie: "I'm going on a date with Thad tonight."
Kara: "Why not go on a date with Brad?"
Susie: "Ew. He's got real button down shirt energy."