The Nick Frost character is an unlovable, shiftless, gutter-mouthed slob with zero social skills. This is perfectly communicated by making his first line in the film :-
"Can I get... any of you c*nts... a drink?
I've blanked the offending letter "u", because I'm chicken about getting my blog closed down. The "c" word is still THAT offensive to a number of people, which is why it is perfectly right to use it in this context. Artistically justified, maybe even artistically necessary.
But someone did an inexpert made-for-TV edit and dubbed the word "cocks" over the top.
I wouldn't have minded the kind of edit they do to make radio versions of gangsta rap records; just slurring the word so you can't be offended by it.
My gripe is with the substitution of the word "cocks" and the god-awful editing, which kills the whole scene dead.
Comedy (and Art in general) sometimes needs to say shocking things to work. When you mess with that you need to do it carefully.