Because 7 8 9.
Hey Microsoft, why is there no Windows 9? You've given us 7 and 8, and now you're skipping straight to 10?" "Well, to be completely honest, 7 8 9."
Because nobody gets it.
9 polar bears
9 mouths
Because he doesn't exist.
At least Pluto exists
Because 7 8 9. (7 ate 9)