Wait... you wanted pretty Christmas Photos!?! Me thinks not!! I'm just going to bite my sister's face so she doesn't get any treats!!
This is actually cued behavior but she's only supposed to bonk her with her nose. If you look closely, Phoenix is leaning into her. Phoenix is rewarded very well for putting up with her overly enthusiastic sister!! :D Don't feel too bad for Phoenix, you should see some of the crap Zoe has to put up with!!
I did manage to get a few good Christmas Photos, although they did get tired of it after a while! I've been practicing with my camera in full manual.