Hi , actually i'm stuck in a situation with this girl that liked at first , everything was fine , i touched her hands few times and so she did but here is what happened next:

So there is this girl in my class(23 and im 20) who used to be playful with me for at least few days but then she's changed to something totally different , she responds in a mean way or she starts acting bitchy for really small reasons , i don't know whether it's her attitude or what , yesterday she was really mean to two other guys whose she'd never had an interaction with , actually she mocked one of them in front of me

I don't really care why she is acting like this anymore as i'm losing my interest in her , the only thing i want to do is to put this girl in her place and make her to give up and stop pretending to be tough cause she is not , and the best way is to disarm her bit*h-shield and then ignore her , but i don't know how , i mean , if i stop being playful with her that kinda means i'm afraid that she will act bitchy if i do so , and if i joke or mock her in a playful way she will really insult me , what is the best strategy ? if the answer is to continue fighting then how my responses must be if she insults or act bitchy ? and i don't want to come off as the guy who takes all the insults and do nothing about it. and i feel like saying "i thought you were nice" and these kind of responses are weak and means "since you act bitchy i can not have fun with you" but i want this to be "although you act bitchy but i'll go on having fun with you" instead.

I think there is no better place than PUA to share the story with , i'd really appreciate if you can give me some tips....

BTW this is what im planning to say: (check if it's a good response)
next time i do something and she insults i'll response with a playful tone: "look , if you keep acting bitchy then i'll spank you or you can stay away from me since as you said... you don't dare doing anything"
*One time during a conversation about teenage years , out of the blue she said that she can't trust someone for a relationship and she is looking forward to find one , and that she doesn't dare doing anything unlike her teenage years!
What do you think guys ?

girls have this thing, it is called PMS, it happens when they are on their period,

I wouldn't read too much into it, don't react to it she will be normal in a little while

IMHO the best things to do are two:

#1: ignore her when she does that:
when she insults or teases you in a bad way pretend like it's never happened, ignore and don't respond, she must get absolutely no clue from you that what she's saying is existing and affecting you. Just keep talking about something else.

#2: use positive reinforcement:
like dog training, reward her when she's nice to you with a compliment, this way she'll be compelled to act good

I really wish it was that simple , but it's crystal clear she is acting like a tough girl and the problem with this kind of girls is that people say they are seeking for attention and suggest ignoring them , if you do ignore them in end they are the satisfied ones , and if you give them the attention , they are satisfied again , but there is a misunderstanding , what i think is that usually the aggressive or the needy responses are the ones satisfying her , so that's why i'm looking for some kind of unique attention to her bitch-shield and i came up with the response i posted above , i don't know how good the response is....

Actually this is the one i've been doing , yesterday there was this little discussion over a definition of a word , it just took 15 seconds until i called the teacher since he was around to ask if the definition i was saying was right , and mine was correct and to make sure i also asked him if her definition was right or not , and actually her's was wrong , so right after this she started accusing me being obsessed with showing off that i'm better than anybody els in class and that i was intending to humble her front of the teacher....(she didn't say it loudly) i was shocked cause even for 1% i didn't mean that , so i just leaned back on my chair with a sarcastic smile , after she was finished , this time on purpose i told another girl in the group that my definition was the correct one , she got mad again and continued insulting me but i didn't change my face expression....
so as you see , sometimes it's her attacking me for a nonsensical reason like a nasty dog , and even if i reward that nasty dog , she will bite me someday again , i want to take the power and this reward thing is good to use for later but now i want to say something to show that i'm the one in control and later i can do the dog training , and ignoring her is getting kinda stale as well ,it didn't work on her