Extremely dangerous. Get out of the the house as quickly as possible. Can be caused by anything like electrical fires, portable heaters next to flammable materials, cooking, or smoking. Call 911 for fire department dispatch immediately after exiting and moving away from the flame engulfed house. The CPSC (Consumer Product Safety Commission) recommends testing your fire alarms regularly and replacing the batteries once a year.
A plastic toy that shoots soft projectile darts, often with suction cups on the tips. Fun, safe, and dangerous all at the same time.
Small balls of dust, fluff, and otherwise nose-tickling fuzz that lives under your bed are affectionately known as "dust bunnies." These elusive bits of conglomerated particles tend to be just out of reach of the broom or vacuum cleaner. They usually inhabit places like closet shelves and under furniture. Should you be lucky enough to catch one, a dust bunny would probably look like the picture below.