"I myself have been in that situation and ..."
I immediately think the person writing it is a pompous git. "I myself"?? That would be opposed to "I someone else" then? Or "I in proxy"? "I (actually my dog)"?
Apparently it isn't actually grammatically incorrect, and the 'myself' is used for emphasis. So when a person uses "I myself" they're essentially saying "I, yes I" or translated into internet speak, "MEMEMEMEMMEEEEE!" Except in a really pompous way. And I can't quite pin my finger on why I find it pompous, except it gives me that self-important vibe, like the 'myself' gives 'I' extra authority. Check it out:
1. I saw Pink Floyd live at Western Springs.
2. I myself saw Pink Floyd live at Western Springs.
I don't think the second sentence makes it seem as though I was more there at the concert, or that my concert experience was more valid. It just makes me look pompous. I am important because I add 'myself' after 'I'. So you should listen to me.
Which makes my rebellious inner self go "Fuck you, shan't." And my Tall Poppy Syndrome want to take you down a peg or two.
Because my life is that exciting - yes, I get riled over grammar.
Oh sorry, I myself get riled over grammar.
 And for some reason I now feel compelled to admit that I find the relationship between the brothers in Supernatural both fascinating and profound. Yes, I know the acting and storylines are cheesy. I know the makers seem to be out to offend everyone they can think of. Yet.. I'm compelled by watching Sam and Dean interact. And not in a slashy way either. #mysecretshame