The same as "beer muscles", where when a person is drunk, they do and say things they wouldn't normally have to courage to do, or say. Internet muscles are where a person gets online, reinvents themselves, and says things they can't say in public, like using racial slurs for example.
Guys who fiercely defend each other, even after proven wrong. They do this with such intensity, that it would seem they have feelings for each other.
You could tell that Damian really is David'sbrokeback biatch. Even though neither one of them has any real proof to the contrary, he still defended David's theory that Jordan would've left the Bulls like Lebron left the Cavs. Even after Jordan publicly said he would've never done what Lebron did.