Reddit.com is a very popular and free website, with 1.2 million subreddits, a lot of which are NSFW. In case you are utterly clueless, NSFW stands for Not Safe For Work, and when talking about Reddit.com, it usually implies that that subreddit is filled with adult content. That involves either nudity or something that would not be appropriate for a minor to see. To be fair, that is a rather broad subject, but you get the gist.