Double negatives are actually common in very informal English. If you go to Britain or the US, for example, you'll hear people saying things like "I ain't got no money" in all sorts of places: in pubs, on building sites, in street markets, at football matches.
You may also hear other examples of non-standard grammar, such as 'He don't know' and 'You was there' or 'You done good' from native speakers. These constructions are not correct in terms of the standard grammar of the language, but the speakers are not making mistakes: they're merely using the form of the language which people around them are using.
If you come across non-standard grammar such as "I can't see no ring" in TV or movie scripts, or in books and comics, it is deliberate. The writer wants you to know that this is not a well-educated person speaking. Trolls, I presume, come into this category.