“ In ancient China, women bind their feet for cosmetic reasons, resulting in them not able to walk without help and walking in a shuffling gait.
Possibly this can be modified such that people do it for less stupid reasons.
Disclaimer: This is NOT a racist remark since I'm Chinese myself and hence entitled to freely judge Chinese customs. NOT sexist either since I'm female as well.”
“ Another real world thing. White tea. Can only be picked two days a year, the two days before the flowers blossom. Could be a similiar plant that...is the deadliest poison known, cure known diseases or psychosis, or a potent herb that just tastes awesome.”
“ All magic is suddenly gone. No mage can sling sorcery anymore. This upsets all empires and civilizations. It is soon discovered though, trough the combined work of mystics, scholars and dreams, that all the magic has been drawn into a single orb in a vast tower located at one of the poles. Whoever gets there first wins the greatest price in history, access to all the magic in the world. But who owns the tower?”