An alternate spelling of "comics", a short term for comic books. It was coined in the heyday of underground comics. It was an attempt to convey the true nature of comics as an art form (all comics, not just underground). The idea being the prefix "co-" meaning what is usually does and "mix" for a mix of illustration and written word, as opposed to the term "comics" which the general public viewed as something for children. (note: i'm just going by what I learned in a college course for comic book history)

Underground adult oriented comics that are the alternative to the mainstream super-hero stuff

pornographic comics or comic books

The urban slang version of the plural "comics". Something that idiots use when they want to sound 'hip' and 'cool'

A strangely comical mixture.