I can't count the number of times that someone would not accept "I'm not interested" as a legitimate reason to back off. I refuse to use "I have a boyfriend" unless I feel I'm in danger. I'm not going to excuse such none sense. If they ask and you say "no," and they say "Why? Do you have a boyfriend?" You say "It doesn't matter. I said NO!" If someone justs asks me if I have a boyfriend, I say "Why do you ask?"
"Oh, I'm just curious"
"again, why?"
"I just wanna know"
"What does it have to do with you? How is it any of your business?"

Or if all else fails "Piss off!"

I always say "I don't date men"...'cause I don't...It works, and they always leave...(usually grumbling or something, calling me a bitchy bush-munching lesbo or whatever other sexist gay bashing insult the stupid fuckwit can think of).

But I understand what you're saying...I've seen women who tell men straight up that they "aren't interested" and for some reason certain assholes take that as "she's just playing hard to get, so she must really want me" and then he continues doing what he was doing even though the woman told him that she's not interested! I don't get it. It's really sad that women say "NO" and certain men just don't get it.

Thus, my best guess would be that invoking the whole "fake boyfriend" thing probably works better than saying "I'm not interested" otherwise you would just say "I'm not interested" if it actually worked (which it doesn't seem to)...Maybe when some men hear "I've got a boyfriend" they think in their heads "gee, well maybe her boyfriend is bigger than me, maybe he would kick the shit out of me...well, I better back off cause I don't want a potential beat down from another man"...and I'm sure that whole train of thought involves many gender stereotypes and sexism...but again I can't be sure because I'm just taking a stab in the dark here.

So, I can only speculate what's going on in their heads. What is for sure is that women should be able to say "NO" and expect to be listened to. Women shouldn't have to rely on saying to a man basically: "sorry, I'm already someone's 'property'". Ugh. I'm sure someone could explain the sexism and gender stereotypes / enforced gender roles, implied in that statement better than I can.

I certainly don't know what going on in the heads of those that don't understand what "NO" means. Maybe those guys are just mentally deficient or something...I mean, how can anyone not understand what "I'm not interested" means?!?!

I don't think "I have a boyfriend" necessarily implies that you're property. It just implies that you're monogamous.

It works for a number of reasons. A lot of those creepy guys probably will think of it as you being property, and that's annoying. A lot of them will just assume you're being coy until you bring that up. If you have a boyfriend, you're not going to hook up with them. Of course it's dumb that they won't just accept your FIRST no, but that's why we call them creeps.

i don't have a problem with using it, although I tend to use it on guys I don't want to hurt rather than guys who creep me out. Witch creepy guys I'm just really rude.

If all else fails, start crying about how you just discovered that you have a bunch of STI's.

Meh. I kind of agree with nattles, except for, it only works about half the time. The other half of the time, I get lines such as "what does that have to do with me?" or "I'm married too, let's not tell". So I don't use it anymore. Now I say no and walk away (if the guy seems pushy or assholeish), thanks but I'm not interested (if the guy seems nice, respectful and non-confrontational) or EW.

EW works the best because they just don't know what to do with that; it's unexpected.

How about: "I'm so glad to meet someone who's open minded about a woman with a serious mental illness! (in my case it's true). I have a temper but I take pills for that. And I only have one meat cleaver at home. How about you?"

"I'm sorry, I don't date outside my religion...Mithraism."
(If he replies, "No way! I worship the Sun God Mithras too!" he gets a second chance.)

I've used the boyfriend excuse both in and out of relationships. But only when it was clear that "no" wasn't enough. It's scary that these creeps, who clearly have no respect for women and their wishes, respect other men enough to back off immediately.

I usually say that my girlfriend wouldnt appreciate it. And while I am not in a relationship with a girl at the moment, I date both men and women, so it works. Plus, men just presume that I am a lesbian and move along.

I am not sure that it is P.C., but I consider my sexuality to be about me, so I don't worry about being a representative of other bisexuals.