Yes, the “hanger reflex” is real (and here is the study to prove it)
Studies prove that it works on 95.8% of people

The other day I watched this video on TikTok of someone taking a clothes hanger, putting it on their head, and their head turning to the side reflexively.
옷걸이를 벌리고 머리에 쓰면 목이 저절로 돌아간대요 pic.twitter.com/OnmIiEz2LL
— 비디오계정 (@b_ideo) September 24, 2020
Obviously I immediately grabbed a hanger from my closet to try it out. My scepticism be damned, when I put the hanger on my head moved automatically to the side.
Intrigued, I fired up OA.mg (a search engine for open access research) to see if this effect had been researched.
Turns out the so-called “hanger reflex” was studied by Japanese scientists in 2015. They tried it on 120 people between the ages of 19 and 65 and observed head rotation in 95.8 percent of subjects. The effect is consistent in males and females. In 85.4 percent of the trials, head rotation was observed in the direction away from the hook.
You can read the study here: https://oa.mg/work/10.2176/nmc.oa.2014-0324