The fear that your deepest connections with people are ultimately pretty shallow - that although you consider them close, you refuse to let them see the “real” you. Due to fear of losing them after you expressing your fears, hopes, or love to them.
When a plate of loaded nachos is delivered, the "keystone nacho" is the nacho chip that, when lifted from the platter, pulls the largest amount of toppings from the plate at once. The person who pulls the keystone nacho is hated, respected, and envied by all others at the table.