Someone who writes/comments on youtube videos/forums and argues with other people or insults other people with extreme confidence (confidence that they normally dont have) due to the anonymity of the internet.
If you tell someone fuck you in real life, they might kick your ass.
If you tell someone fuck you on youtube, they can't kick your ass because they don't know who you are. So ppl like to use this absence of consequence to fullfill their need to raise their self esteem.
Dude, look at this guy talking smack like crazy on youtube, internet tough guys... such losers.