The kind of person that spends time uploading boring and pointless videos on YouTube with the value of being so bad, that they are hilarious.
Commonly, this person thinks they are watched by hundreds of people and act as if they are an important TV celebrity, but are actually only watched by about 3 people. They will make announcements such as upcoming videos, why they haven't posted videos recently and other shit people do not care about.
They will also post video responses to other users which actually have a decent audience so that they can get attention, also trying to emulate popular memes and web videos, but tend to miss the point and fail miserably.
YouTube Boob: "Hello YouTubers, today im going to rant and review about Sonic The Hedgehog, in a pretty much sense it is.."
Big breasted teenage girls who make YouTube videos in revealing tops commenting on the most popular videos because they are too dumb to come up with their own content.
Today, I heard Betsey talk about the new Twilight movie in class. She is too flat chested to do YouTube Boobs.
The person who makes a youtube comment that has to do with the number of people who liked/disliked the video
Person who lives at home: "Hey ma, I just commented that 55 people don't like to raise their glass like Pink."
Mother: "You're such a youtube boob"