Ruby's Sugar Stash is a thing that appeared in the short The JingJing Squisher (10 year anniversary). After an object eats some of it, they become extremely hyperactive. Proof of this is that when Ruby has some, she talks extremely fast.
According to the writing on the wall, Ruby has eaten 73 of her other stashes.
The object appears to be a pile of white sugar, located in the corner of a wall. The stash seems to have a hole poked into it, which most likely is caused by Ruby, whose shadow is seen on the sugar. There is other sugar around the stash, too.
The sugar stash was misconstrued to be a pile of cocaine, which caused small amounts of backlash, which Cary apologized for in his video, "Cary's BFB 6 behind the scenes - More recording of lovely lineys".
According to the shape of some of the flakes of sugar on the outside, it isn’t physically possible.