First, it's important to remind your friend that she doesn't need to let her boss' jabs irritate her and seep in. If you teach her to avoid taking everything personally, she'll be better off and will be able to stand on her own two feet when a problem arises.
Next, encourage your friend to keep a smile on her face and try to take everything her boss says with a grain of salt. It's more important that she gets her job done on time and efficiently than worrying herself with what her boss thinks.
If your friend seems to be suffering from an enormous amount of stress from her job, you might want to recommend that she speak to a psychic. Through a series of psychic readings, she may find that it's in her best interest to look for a new position where she doesn't feel overwhelmed by her boss.