The comment section on any site is like a big bulletin board on the internet. A bulletin with trolls, illiterate people, and random advertisements. Sometimes there's even a legit comment thrown in there. But most of it just makes you want to find the person who posted it, go to their house, and sodomize them with a shovel (insert visual here). This has been reiterated to death, but there really needs to be a way punch someone through the internet.

Some places have worse comments than other though.  I have to leave 4chan out though being that it is basically all comments, most of them being trolls.  Out there somewhere, there are some places that I really hope are actually trying to leave completely horrible comments on purpose.
I Can Haz Cheeseburger holds the title of most incomprehensible.  Half of the time I have to sit and try to figure out what the picture says, but reading the comments just makes my brain hurt.  It's like they took a hearing impaired monkey and told it to write out human speech phonetically.  The complete lack of anything that resembles English or grammatical rules just stumps me.  You know, I bet if cats could talk their syntax would be just fine.

Youtube comments usually revolve around putting down others tastes in music, sense of humor, making judgments on people's sexuality, and making excuses for why people hit the dislike button.  These comments usually involve something such as just plain missing the button, Justin Bieber fans plotting world destruction, or just being too enthralled by whatever the video is that they accidentally hit "dislike."  These comments are some of the shovel-sodomizing ones, but every once in a while you get something creative.

*makes witty comment about why people disliked this video in hopes of thumbs up*

I can't understand why people would go to a video that they don't like to make a comment about why they think it sucks. Maybe one day there will be some sort of way to keep people from posting retarded comments.