Well, that term is new to me.
It refers to the tendency of some singers (such as Mariah Carey, Whitney Houston, and far too many people who think they can sing better than they actually can) to draw out (or "oscillate") notes-- excessively, some would say.
Yes, I remember when I first noticed singers doing that. I think Whitney Houston was the first I noticed (or rather, a girl in a talent show singing one of Houston's songs)-- and ever since it was popularized (in the 90s?), it's been a menace to my ears.
Nope, not a big fan of the urban yodeling, I have to admit. I don't think I can take much rural yodeling, either. All yodeling seems like one of those things that are more fun to do than to listen to.