Alex Meneses (Stefania) was on "Friends" in "THW Chandler Can't Remember Which Sister". She played Cookie, the sister who hits Chandler.
While her anger at Robert is justified, it's possible Stefania misunderstood Robert when he called her annoying. In Italian, "noioso/noiosa" means boring, not annoying. It's probably why she not only threw the pretzels, but also took Robert's work shirt off and threw it at him - an attempt to show him just how interesting she really is.