In real books, I use real bookmarks.. not cereal.
Do that with a book I lend you & you won't be able to run far enough!!! (The same goes for 'dog-earring'!)
& yes, I still use "real" bookmarks (some I've actually gotten as gifts) but will also use business cards & the jokers from playing cards, etc. ...
My favorite bookmark is one that says I read banned books. I have had to replace it several times, I'm going to just print more copies and give them away rather than surrendering my old one.