GF needs to needs to figure out the difference between a possible home invasion and roomie comming home drunk.
Perhaps I am too far removed from the Animal House lifestyle, but I disagree with putting the onus on other people to determine if the threat with which they are presented is because of drunkenness. (Do you think anyone ever pretended to be drunk in order to get away with something?) If a person drinks to the point of not being in control of themselves, they need to understand that that degree of drunkenness is itself a choice which may have adverse consequences. A threat is still a threat whether it comes from a drunk or a sober person.