It is wrong to spit into the food of others.
Christina is working at Subway and is taking the order of a woman who once bullied her.
Christina wants to feel better about her former bully being in the store with her.
Christina asks her manager if she can go into the back for a moment to get away from her aggressor.
Christina waits until the customer's back is turned and lets some of her saliva fall into the sandwich.
Christina's boss understands and takes Christina's former bully's order.
Christina's boss sees her unhygienic action and terminates her from her job.