Someone's face doesn't fit means: Used to imply that a person's appearance, personality, behavior, or background makes them unsuitable or unwelcome for a particular job, group, or situation, regardless of their qualifications.. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.