It's amazing how everybody is so quick to dismiss the general public as "stupid" just because they are not familiar with some domain specific terminology.
How many people actually called in? I'm betting a few dozen out of thousands (maybe hundreds of thousands) of listeners.
But it's not. From La Wik [1]:
"Dihydrogen monoxide", shortened to "DHMO", is a name for water that is consistent with basic rules of chemical nomenclature, but is not among the names published by IUPAC and is almost exclusively used in humorous context.