Everything. On a whim, a friend and I decided to pitch each other dumb ideas for films or television programmes and realized that every single one of them had been or was about to be made, no matter how daft our ideas were.
Same goes for music, too. And art in general.
Even this thread has probably appeared in some form or another before now.
Is originality even possible anymore? If our generation is struggling in a creative sense, who else is relieved they won't be growing up fifty years from now?