Picture is courtesy of sethfrantzman who published it on Flickr and asked:
what is the story behind the Star of David on the left hand side?
I guess the answer is connected to the Mamluks who used the hexagrams also on the walls of Jerusalem.
This blog (by Zeev Barkan) is dedicated to the Star of David, its history, its various meanings and usages in different cultures. It includes thousands of pictures of Star of David, six-pointed stars, hexagrams, Solomon's Seals, Magen Davids and yellow badges,and served as a resource for three books and four art exhibitions.
what is the story behind the Star of David on the left hand side?
Here's another example of a Star of David showing up in a strange place: I think the shirt is promoting some music label or band -- I think it's connected with Rastarianism (there was sort of a Rasta color scheme to the front of the shirt), which uses the Star of David in its iconography too. The shirt is one made in China for the Japanese market.