That's an entirely different question
Lack of an appropriately inappropriate orifice to apply the hamburger from the combo meal to is one possible reason. Worry not fizz, I'll just eat that quarterpounder myself.
More likely, the kind of severe ignorance, repression, and need that might lead to someone behaving this way suddenly.
Possibly compelled speech and/or action from an imperfect spell and/or curse letting her emotional responses still show through, but that would be unlikely and contrived. Further, anyone could be getting mindcontrolled at basically any time, so we can't really go around ignoring everything anyone ever says.