I agree that you use the word "retarded" too much. There are a lot of other words you can use that won't potentially alienate/offend part of your audience.
I also think you need to remember that you're writing for an audience, so remember not to use vague pronouns. For example, on the Rhianna post you said, "Apparently this video is the most horrible video ever made according to these people." Who are "these people?" Is there a specific group? Commenters on a post?
Anyone can say something is "stupid," it's when you explain *why* you think something is stupid that it becomes interesting. Keep working on it!