How do you pronounce the "#" symbol?  It's traditionally "number", "pound" or "hash".  The word "sharp" refers to the musical symbol, which looks like the "hash" symbol but really isn't the same thing. 

So, could it possibly be, that the intended pronunciation for "C#" was "see hash"?  Afterall, that would make perfect sense for two reasons.  First, the word "hash" is commonly used in programming as in "hash table".  Second, it's a slang word, just like "java", for something that comes from some tropical island that's consumed. They "innovated" everything from Java, why not go the extra mile by using a "hip" name?

Matter of fact, it's wholly appropriate.  After all, the intent of the pusher (in this case the vendor),  is to have the user "hooked" (in this case "locked-in") so he can peddle more of his stuff!