SlackeryTurnBull

Apparently it's a reference to the video of a rat in New York that was carrying a slice of pizza in the subway. Still, seems an odd reference to make. The "Pizza Rat" was a thing from like a year ago.

Beaucephus

The Pizza Rat is literally a rat that grabbed a slice of pizza (in NY I believe) and dragged it across the sidewalk. As in a large mouse. Raton in Spanish. An animal. Literally a member of the vermin species or some shit like that.