This trope is a slapstick comedy equivalent of a binary explosive. It consists of two completely harmless elements which, when combined, Hilarity Ensues.
First, there's an animal. It's usually either a baby wild animal or a recently - acquired pet, but it can also be an older animal or even a Starfish Alien. If it isn't adorable it'll often be Ugly Cute. The important thing is that it is both (1) seemingly harmless and (2) highly sympathetic.
Next, there's a scene of orderly domestic tranquility. It might be a carefully organized storage shed or convenience store, a restaurant, a dining hall preparing a wedding reception, or a bedroom in a Stepford Suburbia. There are often a number of highly fragile objects present, such as lamps, vases, wedding cakes, neatly stacked displays, etc.
What happens next depends on how the two find their way together.
- If the animal gets into the room alone, the scene will be a complete mess by the time any humans arrive. The animal will be completely unharmed, although usually coated with some substance it overturned.
- If there are already humans present, expect everyone except the Only Sane Man (usually either a child, the animal's caretaker, or a minor authority figure such as a hotel concierge) will be either oblivious or panic and run for the exit, causing more trouble than the animal itself. Hilarity Ensues as the Only Sane Man crawls under tables in an attempt to locate the animal and is mistaken for a troublemaker. The scene will typically end with the Only Sane Man being verbally chewed out by an angry customer, their boss, etc.
If there's an older pet who is largely innocent of the damage, expect it to be blamed for cute animal's damages.
Unlike a Killer Rabbit or Happy Fun Ball, those of this trope are not a serious risk to life and limb. This animal causes much less deadly destruction - just humorous stuff - for example, trying to jump from a ladder to a balcony, causing a can of paint to fall onto a wedding cake.
It's also entirely unintentional on the animal's part. The animal often either doesn't know it's being naughty, doesn't realize how angry this might make the people who spent hours setting up the room, or it doesn't really know how to NOT be destructive in such an environment. The naughtiness often makes the animal seem even more cute, especially when it is just as frightened by the chaos it is creating as everyone else.
Compare Non-Malicious Monster.
- In Chi's Sweet Home, there is a chapter in which the main character (a kitten) is exploring her "father's" office. She ends up getting a roll of packing tape stuck to her butt and, after a series of event, the office is a complete wreck.
- In Cats & Dogs, the family adopts a seemingly-cute Russian Blue who is actually working for Mr. Tinkles. He frames Lou for leaving a mess on the floor, and he tears apart the living room with all of the dangerous tools that he used against the dogs.
- In The Shaggy Dog sequel The Shaggy D.A., the title character hides under a table at a charity dinner, causing a panic.
- In The Water Horse, the title character is chased by a bulldog through a dining hall in a Big Fancy House, much to the annoyance of military personnel using it as an officer's mess.
- Wild animals
- They often find man made structures and vehicles a highly attractive environment, filled with places for shelter, warmth, food, etc. However, they often underestimate the danger posed by angry humans and their machines. In turn, humans often underestimate the potential for trouble that a seemingly harmless wild animal can have.
- Cute little mice can chew through wood, wires, and food packaging, leave droppings in unfortunate places, and otherwise wreak havoc that seems far greater than such a tiny creature should generate. While they are Big Eaters relative to their size, when you see a mouse there's often more than one.
- Many domestic animals are bred to be cute, sweet, and harmless, but deep down they're still animals, and have the potential to be just as curious, predatory, opportunistic, and feisty as their wild cousins.
- The cat breed known as Maine Coon is notable not only for its coat, but also its size and disposition, which not only makes them more likely to knock over objects, but also riskier to retrieve when riled up. Let's just say it's best to wear long pants.
- Animals with a highly social nature, such as dogs, often get bored or anxious easily when left alone, and some will take their frustrations out on inanimate objects.
- Similarly, highly intelligent exotic animals such as apes or parrots, when not given sufficient physical and mental challenges by their environment, will often focus that intelligence on looking for creative ways to amuse themselves.