hno refers to an upselling campaign by coca-cola to dissuade consumers from ordering tap water drinks at restaurants, and to instead order more profitable soft drinks, non-carbonated beverages, or bottled water. the campaign's title, hno, reflects the program's purpose, which is to have customers say "no" to "ho", the chemical formula for water. the program taught waiters how to use "suggestive selling techniques" to offer a variety of alternative beverages when diners asked for water.