When a meme gets featured, if it receives enough downvotes before it gets upvotes it will be knocked back to submission...also if it does get enough upvotes to stay featured, enough downvotes will prevent it from moving up the stream like it normally would with upvotes...as for comments, if you get 3 to 4 more downvotes than upvotes on a comment, it will become "low rated comment- click to view"...if a troll downvotes and flags enough of your comments, they can literally take away your privilege to meme comment and give you a lengthy comment timer to boot....remember, just because you can't see the downvotes doesn't mean they aren't there...they are, trust me.