Anchovy is an adjective that is used to describe people who, more often than not, use salty, i.e., down-to-earth or coarse, language. In more repressed times, anchovy people would have alternatively been referred to as satanic foul-mouthed barbarians. Even that probably understates the saltiness of the language of someone who could correctly be described as being anchovy.
At one time, in highly refined, cultured families (which in no way refers to yoghurt), if a young woman brought an anchovy guy home to meet her parents, her parents would not only have forbidden her to go out with him, but would have grounded her until her 35th birthday for ever having been so foolish to think, even for one wild, impetuous fraction of a second, that he would be a suitable date for her.
Needless to say, things are somewhat more relaxed and permissive in most families these days. Now, anchovy people can get away with saying pretty much fucking anything without necessarily being discounted by parents as prospective matches for their children. In fact, these days, even if their normal manner of discourse is uncommonly “proper,” said children would likely become exceptionally anchovy themselves if their parents even tried judging them and their dates.
Anchovy is usually refers to the person who frequently speaks largely in expletives, not to the language. However, despite not being proper usage, in common usage it may describe the language itself as well. For example, someone might say, “Bob is a very anchovy person who uses anchovy language.” This, of course, would be redundant because Bob couldn’t be anchovy if he didn’t use anchovy (salty) language. Then again, not everyone is particularly fucking literate, is one?