Have you ever played Ultimate Frisbee? Whenever someone on my team catches the frisbee, pretty much everyone on the other team always crowds around them. At that point, it's pretty much impossible to pass the frisbee without getting it knocked out of your hand. And it's not fair. The rules say the other team has to stay at least two feet away, but nobody ever listens.
Know what I always shout at my teammate? "Hit them with the frisbee! MAKE them back up!" (A great way to measure out the minimum two-foot distance is with your arm and a firm grip on the frisbee!)
You know what usually happens? The guy with the frisbee doesn't listen, lets himself get crowded, and drops it. Because it's not an action that comes naturally. When you're hanging out with your friends in the park, throwing the frisbee around, and one of your friends walks too close to you...you never jab the frisbee into their chest and shout in their face.
When you're hanging out with your friends or shopping at the mall, there is hardly ever a situation that requires you to break the rhythm of whatever's going on, get in someone's face and say (slightly louder than usual) "Hey! You need to stop doing that. NOW." You have zero muscle memory for this sort of thing. So you freeze up. It's nothing to be ashamed of. It's the reaction that comes most naturally. That's why police officers, soldiers, etc. do so many drills. They're developing muscle memory.
I'm not saying you should drill for this. Just remember it next time you're in that situation. You don't even have to wait until someone touches you. Unwelcome flirting? Mention that you have a boyfriend in casual conversation. Doesn't stop? Say, "Hey! Tone it down. I told you I have a boyfriend." Tries to deny it? Say, "I don't care! You were still making me uncomfortable." Still doesn't apologize? Leave.
It's perfectly justified. Just remember that you're the one who's right.
Touching random intimate bodyparts is not flirting in my opinion. Lack of interest can be misinterpreted as "she's fine with it". Douchebags aren't even 'people', I mean would you let your dog hump you? Well, I assume that if you're not a pervert then you wouldn't.
Anyway, I think flirting is okay as far as words go. Touching is past the fine line of child's play. That's more of a move on you.
I think it's polite to dump others with modest honesty:
"Sorry, but I have a boyfriend." "Sorry, but you're not my type." "Sorry Mario, but your princess is in another castle." "Could you stop bothering/touching me? It's embarrassing."
Im 29 years old and still dont get what girls "expectations " towards flirting is, quite frankly i dont get it, its like a little game i find irrelevant sometimes, maybe its because im more direct towards what i want and i like cut through the bs.
I'm really "sensitive" in these kind of things. If it's someone I'm chasing, flirting is awesome, if it's a friend then I politely say "thank you" but if it's someone I don't know...boy does my brain sound the alarms. I hate it, I truly do. The last thing I advise you to do is to smile. You never know who is that person and how he might perceive that smile of yours. Next thing you know you are screaming and running down the street