I am not exactly what triggered this to happen, but I will try to do my best to explain it.
I had just gotten the Sheep's Clothing achievement (see solution here)
Right afterwards, I opened the menu at the upper left corner of the screen. I then select the exit icon (not single back arrow icon or the picture of the little man exiting (which will close the game), but the other exit arrow.
Once I did that, I was back at the character selection screen. However, this time, every time I pressed a button to select a character, I got some sort of meat product instead.
I pressed all buttons on two controllers to fill up all the character slots with different meat products and pressed
to start the game.
This made the achievement unlock.
Not sure if this was triggered by something specific, or just entirely random.
Any input in the comments section would be appreciated.