It’s called Voluntarily Generated Piloerection (VGP)—the ability to consciously give one’s self goosebumps. I’ve never met anybody else in real life that can do this so thought surely there must be at least one other person on here who can! If you can, how do you trigger yours? Mine is a form of what I can only describe as electric energy at the back of my head which I force down the entire length of my spine, I do it about two or three times rapidly one after the other and the skin on my arms, legs and chest immediately flare up with really strong visible goosebumps 
- almost like a plucked chicken 
The example given in the article says the guy moves his head from side to side to trigger it but i do it completely still, just concentrating on making my muscles send the sensation down my back.
Please join me, fellow freaks of nature:
A mammal’s hair follicle clings to the skin via a tiny muscle. When this muscle contracts, the hair will stand, the skin around it will undergo bump-shaped distortion, and voila—goosebumps.
For the 1499 people in this statistical metaphor, goosebumps are completely involuntary. The tiny muscle, called the arrector pili, is made of smooth muscle fibers. And like other smooth muscles of the body—those that handle digestion, blood flow, respiration, and so on—they are unconsciously regulated. The nerves attached to them lie in the autonomic nervous system, the part of the nervous system dedicated to managing bodily functions you aren’t supposed to control consciously, like heart rate or pupil dilation.
www.mentalfloss.com/article/622399/people-can-control-their-goosebumps