Out of all the animals Angry Grandpa Hates, Cats are by far his least favorite Animal. They have been his most worst animal since he began on YouTube. He hates the way they meow and do nothing, and considers them to be very annoying. In his old trailer a bunch of cats lived under there and Angry Grandpa had to be tortured by hearing them meow under his floor. Even though they were kept alive, Tina went as far as giving the cats milk and turkey, making her husband even more angry for feeding them because now they wouldn't leave.
It is revealed in on of Michael's vlogs that Kimberley told a story about how AGP loves cats. Kimberly said that Grandpa owned a cat named 'Muffin' that he loved, and "took everywhere," but as soon as it passed away, Grandpa's love for felines took off. Charlie denies the story - going so far to destroy his toaster to scare away Pickleboy, who kept asking him about Muffin.
Appearances : Cats are mentioned quite a bit throughout Angry Grandpa's video. In 100 Ways to Love a Cat , Angry Grandpa is asleep when Michael turned on the video at full blast, leaving his dad to endure 35 minutes of ways to love a cat since it was literally 100 ways. The prank was pulled again several years later in "Angry Grandpa-100 Ways To Love a Cat - Part Two ," where Michael rigs the door knob while Angry Grandpa is sleeping, and Bridget runs a wire under the door to the stereo and plays 100 Ways to Love a Cat while Michael is filming him, but this time Angry Grandpa eventually finds the stereo and breaks it.
However, Tina decides since she's going to move out soon, she adopts a cat named Princess and cared for it in his house.  Angry Grandpa finds out immediately and throws a huge fit, threatening to kill the cat with The Annihilator. However she moves out before anything worse happened.
More appearances were made such as Angry Grandpa going under the trailer to fix a wall, which causes cats to meow, infuriating Angry Grandpa.  One night as the couple were asleep, Michael turns on a loud YouTube video of cats meowing, waking up his dad into a furious rage. The couple begin to argue with each other and at Michael to turn it off. When Angry Grandpa was sleeping Tina and Michael put gum in his beard and hair and also stuck pictures of cats with superglue.  Also, Michael forced his dad to watch over 10 minutes of the Nyan Cat which infuriated him and threatened to break the computer if Michael didn't turn it off. 
- Angry Grandpa vomited after kissing a cat.
- Angry Grandpa had to kiss a cat for reaching a certain number of subscribers. 
- Angry Grandpa had to eat cat food along with kissing the cat, and nearly threw up from it.
- Angry Grandpa said that he hates cats more than he hates Obama.
- Angry Grandpa once decided to feed the cats living under his old trailer in hopes of Tina not letting them have his good food.
- It was revealed by Kim (As shown here) that Angry Grandpa used to have a cat named Muffin and ever since Muffin died, he hated cats due to Grandpa still being upset that he lost Muffin.