Because parents and teachers naturally find these expressions alarming, they may fear these children have deep-seated anger issues, suffer from depression or abuse, or are on the road to juvenile delinquency. When these children have frequent negative outbursts, they're often referred to therapists. Of course, this kind of behavior must always be carefully assessed to be certain the child isn't dangerous to himself or others, and isn't being put in danger by home circumstances. But often it's their temperament speaking, not any pathology.
You always know how intense children feel. It's important not to escalate with them (they can out-escalate you). Speak in a matter-of-fact tone of voice with them, send them outside to yell, or suggest they talk it over with their bear or to their audio recorder. At a calm time, you can help them learn to choose words more wisely to express their negative feelings in ways that don't alarm people.
Sensitivity is a measure of a child's sensory threshold. A child who's low in sensitivity is better equipped to handle a stimulating environment, such as company or a shopping trip. A child high in sensitivity has a low tolerance for these settings and is prone to falling apart with too much exposure. Sensitive children are very reactive to physical stimuli--sight, sound, taste, smell, and touch. They may react strongly to soiled diapers, tags in clothing, snug elastic waistbands, and scratchy material, lumpy foods, or a noisy classroom.
For years, my highly sensitive son found jeans too uncomfortable and lived in sweatpants. He rarely wore jeans until the seventh grade, when sweatpants were suddenly not very cool. Thankfully, he could tolerate the baggy jeans then in style. When parents learn to make adjustments, such as cutting tags out of clothing, this issue becomes more manageable. Parents should refrain from jumping through hoops, however. They might respond sympathetically when, at a restaurant, the right brand of catsup isn't available ("Oh, that's too bad"), without dashing out to buy the preferred brand.