Ubuntu 16.10 will be codenamed "Yakkety Yak". The announcement was made by Mark Shuttleworth on his blog, which I'll quote in its entirety below:
Y is for… Yakkety yakkety yakkety yakkety yakkety yakkety yakkety yakkety yak. Naturally 🙂
As you probably know, the development codename of an Ubuntu release takes the form "Adjective Animal". Initially these weren't in alphabetic order - until Dapper DRAKE (6.06).
Up next: Ubuntu 17.04 Z Z. Will it be "Zooming Zebra" :)? Or maybe Zealous Zorse? We'll find out in 6 months!
For a list of codenames used in previous Ubuntu versions and upcoming release suggestions, see THIS page.
image via Wikipedia