Girl in the first panel is Mai from the anime Nichijou.
I was a tad releculant to post this one. It was originally only going to go up on my Pixiv account since I figured the fine folks from Japan would be the only people to get the joke, and they have been making jokes comnpairing Nichijou and Azumanga Daioh, but what the hell, here ya guys go.
Chances are most of you buggers are gonna like this more for the yuri crack pairing than the actual joke.
And these are probably the best Osaka and Yuki I've ever drawn. And the best I've ever drawn of the two involves them ready for lovemaking. Go figure.