Are you talking about this
arm-cross?
Besides self-comforting or if one is chilly, there is also the times when the wardrobe may not be functioning well. Crossed arms help keep everything in place.
Sometimes it is due to being self conscious of ones shape or the spot the kid just left on one's shirt.
Sometimes we just don't know what to do with our hands. Our pants don't always have pockets. When I don't have pockets I tend to cross my arms.
Sometimes my purse starts to annoy my shoulder and I cross my arms to change the stress point (usually when I don't have pockets).
Those are just a few things I thought of as I walked through the kitchen with my arms crossed.