Who knows?

Tony the Tiger: He's been around since 1952, his frosted flakes might have been Greeeeeaaaaat! but what colour was his nose? Many are saying it's only recently become a prominent blue, whereas they have a false memory of it being black - or is the Mandela Effect at play here?

Few people realise he was created as a result of a competition Kelloggs ran to find the official mascot for a brand-new breakfast cereal. Eugene Kolkey, already a well-known graphic artist, came up with the design, won the contest and he's been with us ever since.

Complete with his blue/black nose...

Origin

The origin of Tony the Tiger was after an ad man called Raymond Anthony Wells, who worked at Leo Burnett where the contest for the new character was being run. the tiger won, otherwise we'd all be discussing either Katy the Kangaroo, Elmo the Elephant or Newt the Gnu.

The cartoon craze from Disney and Warner was in full flow, so Tony's appearance was deliberately styled from these to ride on their popularity. 

It was known he'd always be seen in color, which is a big clue regarding the color of his nose. If it was black and white only, there'd not have been much point.

Although it's obvious real tigers don't have blue noses, there's not much of a reason to make his blue other than just to make it distinctive. When it's pointed out to those who always remember it as black, they either just say thery remembered it wrong and move on, or are genuinely surprised because it seems so obvious to them then, and they can't see how they missed it for so long when it "jusmps out" at them now so prominently.