Is it deceptive or dishonest to call something King Size if a member of royalty has not approved or measured it?

I don’t think so. After all, what exactly is the size of a king? Apart from bed frames and mattresses where the term has been standardized, “king size” is little more than a hackneyed expression vaguely associated with “bigger than normal”.

No, In marketing, king-size is from 1939, originally of cigarettes

I’d have to acknowledge and accept the legitimacy of “kings” or “royalty” first.

It’s passed into everyday usage.

Appoint me king, and I shall put the advertisers in their place…

Who says the King of Steaks hasn’t approved it?

You must be fu…king jo…king

Well, there is the king