Anyone who's read Terry Pratchett's Wee Free Men knows what "waily waily waily" means... if you don't know it, there are "pictsies" (little men who are, well, Pictish, in that they're blue skinned, speak with Scottish accents, and love fighting and drinking) who bewail unfortunate circumstances by yelling "oh, waily waily waily!" (they especially love to do this in groups, like an aggressive form of keening).
I've managed to find amusement in Anya's latest infuriating mannerism by thinking of this line from the book. In Anya's case, this involves suddenly flipping from being happy and cheerful to feeling fussy. She then works herself up from low level fussing up to concentrated snivelling and ultimately full blown wailing, by which time she's forgotten what she's upset about, but she's darn well upset and intends to stay that way. This happens at least four or five times a day, usually about nothing of importance, more as if she's checked the clock and thought, hmm I haven't fussed for a while, better do it again.
So far we've managed to stay pretty even tempered about it, simply telling her we can't talk to her while she's wailing, but it is VERY annoying and tiresome, and I hope she stops doing it soon!