Several subreddits have policies that will ban you automatically, even if you've never participated in their subreddit, for participating in other subreddits. F

Several subreddits have policies that will ban you automatically, even if you've never participated in their subreddit, for participating in other subreddits. For instance, the most famous one in my memory is that posting in /r/the_donald got you automatically banned from a number of other subreddits.