I've never seen nor heard of it before either.
But finally after reading it aloud, put the first two words together ...
"SofaKing" followed by the word "angry" and instantly got it.
It's a derivation of a common joke among leftist scum when they assert their superiority over people with the characteristic traits of Downs Syndrome.
In that context, the line would be, "I'm sofa king wee Todd head". I usually respond to assholes I catch saying that (in that context), "Yes; yes, you are..." and walk away.
Have I mentioned I really dispise bullies?
