Where in the world are Trader Joe’s warehouses? (2015)
Trader Joe's presents an interesting punctuation problem.  The most common rule, I think, for forming possessives is rule #1 of Strunk and White: "Form the possessive singular of nouns with 's. Follow this rule whatever the final consonant."  But Trader Joe's already has an apostrophe.  Should the proper writing of this headline should have been...Where in the World are Trader Joe's's Warehouses?Or should it have been...Where in the World are Trader Joes's Warehouses?