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The prize that was never there
Not bizarre so much as instructive: the promotions where the top prize could not be won.
The most genuinely strange category is prizes that were advertised and were not actually available. In the 1990s and 2000s, several large fast-food and beverage game promotions were found to have had their top prizes removed from circulation before the pieces ever reached customers.
The best-documented is the McDonald's Monopoly fraud, in which the man responsible for security at the printing firm took the high-value pieces for years and distributed them through a network of associates. Roughly $24 million in prizes went to people he knew. The FBI investigation was called Operation Final Answer.
McDonald's was a victim rather than a perpetrator and paid out again afterwards. But it is the reason a modern promotion of that kind publishes a seeding and verification process, and it is why "all prizes are awarded" is a sentence with legal weight rather than a friendly reassurance.
The pattern behind the weird ones
Nearly every prize on this list is strange for one of three reasons. Somebody had an asset they could not sell and a contest reached more people than a listing. Somebody wanted coverage and worked out that a ridiculous prize is cheaper than advertising. Or somebody wrote a rule badly and a student with a chequebook noticed.
And the boring lesson that keeps surfacing: the more unusual the prize, the more the Official Rules matter. A lifetime supply has a number in it. A house has a tax bill attached. An island has running costs. The advert is the story and the rules are the deal.