Why would you do dat?

Uh chibi Yukari mad at Ran for taking your attention or breast envy?

Don't bite the hand that feeds you, cleans your house, does your laundry, and pretty much takes care of your lazy ass.

angrybull said:
Don't bite the hand that feeds you, cleans your house, does your laundry, and pretty much takes care of your lazy ass.

Also it should be easy to fix the breast envy problem, this is Yukari we're talking about.

I would have kept this picture if not for Ran's black eye. That kinda makes me sad :(

That's not a black eye, it's a representation of someone going pale with shock or surprise. Granted, it's normally across both eyes, or at least a bit more extended across the face, so the confusion in this instance is understandable.

Ah, that does make more sense, but - the fact that it's only under one eye, I just can't unsee it.

This is indeed humourous and Yukari is being a tad cruel to her. According to the artist comments, Ran is supposed to be babysitting Yukari and, from what we can see, Yukari doesn't like that.