I had to search symbols that have been changed their meaning with the time. The first symbol that came to me was the O.K one, researching the symbol and the letters O.K I found out that there are many and many theories about the beginning of this international expression. The one I heard from my great grandpa was that soldiers use to do that typical gesture and say O.K when they have 0 dead in their troops or 0 kill.
The 3rd picture is my favorite, I was walking around Manly this morning and found this lovely piece of art. The heart is made of old thongs and in every single one there is a message from the people who place it on the fence. Searching for the meaning and the emergence I found out that hearts were used by Magicians and Alchemists for incantations pertaining to matters of love and romance. Since then this symbol has been used to represent love, joy etc...