Sheep Taxi

"One taxi- BEEP BEEP I'M A SHEEP!"

Sheep Taxi is actually a true Gregory meme using Sleepy Sheep and The Taxi (figure out it's real name on the wiki plz) combined with ASDF.

His attacks is a reference to ASDF. 

Body
He looks like The Taxi, but instead of "Do you remember me?", it is instead "Do you MEOW YOUR COW?" and with Sleepy Sheep in the Taxi.

I like Horses.
This is the attack he commonly uses. Apparently when he uses this attack, he summons a train full of horses.

Here's YOUR Cow!
Basically, he appears big on the screen, holding a cow about to throw it, when it gets closer it turns out it won't change it's size. Somehow.