If you've been on Twitter more than 20 seconds you've probably seen WeRateDogs™.
The account does what it promises, using it's own terminology and rating system. Everything is a 'pupper', most 'puppers' receive between 11-14/10 depending on the extent to which they are a 'good boi'.
It's by all accounts a pretty funny follow:
This is Aspen. She's never tasted a stick so succulent. On the verge of tears. A face of pure appreciation. 12/10 https://t.co/VlyBzOXHEW
What defines the trend is its near-onomatopoeic language, popularised by subreddits like r/aww and r/RarePuppers, and, well, videos like this:
Floof = Fluff
Mlem = Dog lick
Bork = Bark
Boop = Pressing/gently poking a dog's nose
Pupper = Puppy
Fren = Friend
Gud Boi = Good Boy
Gud Grill = Good Girl
Doggo = Dog
In addition, you get more advanced terminology, such as a blop:
A blop is when a dog pokes his tongue out due to tiredness/forgetfulness and it often is only a small portion of the tongue. A mlem is basically any time a dog is licking their chops, or sticking their tongue out!
Also you need to intersperse and drastically overuse the word "heck".
Internet linguist Gretchen McCulloch told NPR this is because we want to imitate how we think the 'cutest' of pets would speak:
It's cutesier than others, too. Doggo, woofer, pupper, pupperino, fluffer — those have all got an extra suffix on the end to make them cuter.
You're taking on characteristics of how people would address their animals in the first place.
For a more detailed read into the psychology of why we find these doggos cuter, the New Statesman gave the subject a good mleming.
For a good entry level Doggo meme page, click here.
For more cute golden retrievers like in the top image, click here.