light mask
The public act of using your phone to avoid eye contact with strangers and thus, social interaction. It is a bit anti-social, but we have all done it at some point or another. It is especially visible at night while people walk past strangers.
Diana: omg look! that man's moving closer to us.
Maria: It'll be fine, just pull out your 'light mask' and keep walking.
Maria: It'll be fine, just pull out your 'light mask' and keep walking.