Cohen is shipwrecked and washes ashore on a small island. After exploring for signs of life, he comes across a small village of 3 huts - including two with Stars of David on their entrances. He calls out, and lo and behold, another Jewish man walks out. He explains to Cohen that he was also shipwrecked and wanted to build a proper jewish community on the Island. Cohen asks him - "What's up with the huts?"
"Well", says the man, " the first building, without the start of David is my house; the one on the left, is the shul that I go to."
"What about the one on the right?" asks Cohen, alluding to the other building with the star of david, " Is that the Mikvah? Yeshiva?"
"No," replies the other man, "that's the shul I won't set foot in"