A woman was forced to install a state-of-the-art cat flap to stop her neighbor's cat from constantly getting inside her home, and he is "not happy" about it.

Daisy-May Lee lives in the United Kingdom with her family, which includes small children and her own pet cat.

But the family was repeatedly getting an unwelcome visitor in the form of the neighbor's tabby, who was sneaking in and stealing "leftover dinner."

In May, Lee took to her TikTok account @daisymaylee where she revealed she had installed a new cat flap that uses a sensor to detect a pet's microchips, and will only allow that chip through the door.

She captured the cat's very annoyed expression at no longer being able to sneak inside, leading to hilarity online.

In the viral clip, which has been viewed over 1.2 million times, Lee zooms up at the now-locked cat flap, writing: "Neighbours cat isn't happy with the new microchipped sensor cat flap..."

And as she zooms in, the tabby's face comes into view, giving the camera what can only be described as an unblinking death stare.

She added in a caption: "Hopefully that will stop fluffy owl cat (not sure [of its] real name so kids choose the nickname) from stealing leftover dinner hahahaha."

TikTok users responded in their hundreds, with many, naturally, humorously taking the side of the cat, with one commenting: "You let that baby in now!"

One wrote: "Girl, he's gonna light your house on fire after he steals his 3rd breakfast."

And another joked: "Open the door, or I'm gonna throw rocks through your window."

A third user revealed they had got the same cat flap installed, but the "neighbours cat broke through it with its head. Persistent floof!"

Microchip cat flaps, which can cost up to hundreds of dollars depending on the brand, allow your own pet to come and go as they please by detecting their microchip, while at the same time keeping out strays, or, in Lee's case, food thieves.

While Lee's visitor was a neighbor's cat, stray and feral cats can be found all over the world. In the United States alone, around 3.2 million cats enter shelters each year.

Of those, around 100,000 lost cats are returned to their owners each year, while 2.1 million are adopted, according to the American Society for the Prevention of Cruelty to Animals.

Pet owners finding random animals inside their home isn't an uncommon experience, with a woman recently going viral for recording the moment she came downstairs to find her dog having a "play date" with a neighbor's pet after apparently opening the door for him.

Another became the owner of a stray cat when he simply walked into her home as she was collecting a food delivery, and has remained there ever since.

Newsweek has contacted @daisymaylee on TikTok for comment.

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