There's some confusion running around here it seems.
While I can tell the difference between hand_behind_head and hands_behind_head (i.e. the number of hands), the difference between hands_behind_head and arms_behind_head evades me. And from the posts it's really all the same.
So I guess it deserves some aliasing in one way or another.
Same goes with hands_behind_back and arms_behind.
I can imagine a slight difference in posture, but the current posts don't take it into account either.
Thoughts?
(Not talking about the infamous from_behind tag 'cause I can't even think what to do to with it right now.)
Updated by Xabid