the gays are going about this the wrong way. instead of boycotting, they should occupy.
everyone should take an uber long time in deciding to order. 5 minutes later, after asking about everything on the menu, they should order a small diet coke.
bring a book or a game, sit down, and enjoy your diet coke with unlimited refills. coke does support marriage equality and equal rights for all.
dump the thing out after taking one sip. fill it again. repeat for hours and hours.
bleed them slowly so that legitimate customers will have to wait in endless lines and lobbies packed to the gills with flaming homos reading david sedaris and sipping on diet cokes in suggestive fashions.
that's how i would do it at least.