It's possible (here I am granting Apple artistic license) that they meant "funnest" in an ironic sense, and "Think Different" as "Think [of something] Different" but I am being generous.
Apple might mean to say something in a cheeky sense, but Microsoft tends to say the same thing soberly, and ends up doing a pratfall.
A year or so ago, Apple had a "Sneak Peak" Web page of an upcoming software release, but someone wrote in with a grammar complaint, and it was corrected to read "Sneak Peek." They really should have known better to check the Web page before making it go live like that.