What does it mean to name a patient for your best friend?

What does it mean to name a patient for your best friend? Either your best friend is really sick or you are teasing. But anyway, since we are good friends, we shouldn't give others such an unlucky nickname. Friends should be honest with each other, even if there is something they don't like, they shouldn't give others a nickname behind their backs. It's impolite and friends won't be happy.