I've been away from the board awhile so forgive me if this has been posted before. Just wanted to report that the Shaw's on Western Ave in Brighton has started selling the Mexican Coca-Cola. It's in the juice case in the produce section and also in the ethnic food aisle in the Mexican section.
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The Boston Shaker store in Davis sells Mexican Coke.
Plenty of places in Union Square, Somerville, sell Brazilian Coke (sugared just like Mexican) including the bodega two stores to the left (on the corner) when facing the Precinct bar.
The Boston Shaker
69 Holland Street, Somerville, MA