Hacer la Senal de la Cruz, Hacerse la Cruz

To cross oneself, to bless oneself, to make the Sign of the Cross.

I crossed myself for fear when I saw the class.

In Classic Literature:

"And they cross'd themselves for fear."
The Lady Of Shalott by Tennynson. 

In Songs:

Just one more thing 
Cross yourself, cross yourself 
Come to me 
By Emmylou Harris

In Websites:

"Since we make the Sign of the Cross before and after our prayers, many Catholics don't realize that the Sign of the Cross is a prayer itself."
About.com Catholisism.