Nothing to do with Transformers or OTCA, it's a traditional (old skool) online way of underscoring text which was commonly used back when online boards, chatrooms, email etc. didn't have all the fancy font and board codes that we have now (remember that we're looking at the way online communities operated before the advent of the internet age back when we used to log onto local BBSs via dial up modems like thisOriginally Posted by ITZTRU
).
So back in those days we would do _this_ to underline a word or phrase.
For bold or italics we would use asterisks like *this*. <grin> B^)
Reference