One day I watched a movie where the main character exposed their wrist and tilted their hand back so that their arm/hand was a 90 degree angle. They then preceded to take the tip of a knife and pierce their wrist. Ever since then, I hate bending my wrist backwards. It feels so vulnerable. For instance, I can no longer rest my head on my hand, because I have to expose my wrist for that, and then I imagine it being pierced. Ouch.