How do you pronounce Miscellaneous for 'short'?

Many online forums have a miscellaneous section but call them the “misc” for short.

How would you pronounce ‘misc’ given that miscellaneous possesses no actually ‘c’ sound?

On-line, they are not ‘pronouncing’ it at all; they are just abbreviating the written word, and normally we would pronounce the full word in speaking, just as we do ‘etc’.

That said, I think most people who do pronounce it do so with the /k/ sound-- /misk/-- but keep in mind that when the abbreviation is pronounced that way, it is done jocularly.