Putting on a red motorbike helmet (found on another player), the helmet was clicked and dragged across to my character on the inventory screen and dropped onto my player model.

On the 3D model of my character it showed the helmet, not on my head but attached to my right foot / ankle. This was also true when I came out of the inventory and viewed from 3rd person.

See screenshots.

Eventually it corrected itself after about 1 min. {F28473} {F28474}