Yeah, I've never really thought about that. Then again, I've never tried to go off on my own and scream... though I kind of want to. I've felt that feeling before, though, the one like you can't do something, even though you really want to. You just can't. It feels so impossible that by the time you force yourself to even do something similar, it feels wrong. :(
Your example at the end there, with the girl? Yeah. I can't just stop dead in my tracks and ignore her now, partially because she engages in the conversation first. Maybe you need like a starter, a reason for you to just go and scream. Well, I mean, there are plenty of reasons, but I think you need like a really good purpose for you to just go and do it right then and there. Get someone to piss you off. >:D