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."
That bit just between the butt and the top of the back of the thigh, where if you kind of tickle it a little bit the person has to reflexively and involuntarily sit down.
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.