Cellcurity is a combination word used to describe one's actions to protect their cellphone while showing another person what's being displayed on the screen.
The action usually involves the cellphone owner not letting go of the phone while the other viewer tries to hold the phone. This results in both people holding the phone with one hand.
Person 2: ok, let me see it.
(Cellcurity begins, both people are holding the iphone trying to watch the YouTube video)
Person 2: Man, you suffer from cellcurity!