From the artist:

Yet even more sheep, but this time with a twist: a couple weeks back during one of the stream shows, someone commented that all the sheep I draw have huge boobs.
Now, some of you may not know, but I can be pretty contrary at times, and comments like that can rub me the wrong way - usually not in a negative fashion, just creatively. So I tend to draw the opposite, in this case a petite and obviously flat-chested sheep (I'll find that original drawing and post it eventually) who was very pretty none-the-less. One of the viewers who's an old friend instantly fell in love with the character design and asked to be allowed to "adopt" her. It was intended to be a one-off character, so I was pretty much "Why not?". She named her "Marjorie".
Marjorie showed up in chat the next show and there was a bit of a (playful) spat between her and Molly MacAlister in regards to the various merits of various bosom sizes. Marjorie was sort of winning, that resulted in Molly "silencing" her rival by grabbing her and forcing her into an outfit with huge inflatable boobs. I thought the idea was preposterous enough to be amusing, so Marjorie got drawn in my rendition of said outfit, bouncing around concernedly, trying not to whack herself in the muzzle.