The word is pretty obvious. If you own yourself.
It's actually making a comment that makes yourself look stupid.
Usually used on forums.
Yesterday I forgot my girlfriend's name, and she dumped me.
Oh my God, that's so self-owned
when someone gets self-owned means that the reason of ownage aren't the owning guy's abilities/skills/etc. but the owned guy's stupidity/lack of skills or abilities/etc.
basically said, someone gets self-owned because he does something stupid
who owned him isn't extraordinary, but the owned guy himself is worse than others
similar to selfd
table tennis player 1: (trying to hit the incoming ball while actually hitting the table, dropping the bat and screaming)
table tennis player 2: "haha so self-owned"