Theres actually been these 3 girls who have been showing an interest in me at my college during my Fall and Winter semesters. Unfortunately this is a sad story, since I wasn't interested in any of them. So I had to let them know through my body language.
The typical sort of thing a girl usually does when she is interested in a guy, is a number of different things. They would all try to get close to me but never too close to seem interested in me to the people around them as well as me. They would also look at me for an extended period of time, to try and initiate eye-contact with me.
Girls usually behave in a very indirect manner, which is extremely annoying from my perspective, but I have learned to play their game though, to make sure my message gets across.
First Girl
On the first day of the Winter Semester, all of us students had collected around the outside of the classroom door. I was just waiting at the time, but I got this weird vibe from this girl standing some distance away from me.
A month later she asks, "Did we have any homework?", I reply "I don't know, maybe". The next time we talk, She again asks another question, to which I again respond in a very monotone way, but this time she giggles after.
She manages to build up enough nerve to actually sit right beside me one day, and she then starts to talk to me out of nowhere (just some small talk). Her knees were together and pointed directly at me, showing strong interest in me.
Second Girl
Probably the most annoying one out of all three. She would sometimes follow me outside of class and start walking ahead of me during break. When in front of me she would then slow down in a conscious effort to try and get my attention, and speak with me. She would also do this when I would just be standing against a wall, by walking over and then starting to slow down again, hoping that I'll engage in some tedious conversation with her. All the while she will look straight ahead appearing to other people as though she is just "walking through the hall", but the whole time her peripheral vision is focused on me.
Third Girl
First time I saw her she was in my previous math class during the Fall Semester. She would try and talk to me by offering help while I asked questions to the teacher. One time I asked the teacher, "Shouldn't you also divide the 5 by 3 as well?". " No actually your not supposed to do that...." She gets cut off by the Teacher who then says to me "Oh right, I forgot. You have a really good eye!" To which I respond with a nod and smile. Neither the teacher nor I acknowledged her during this entire interaction. Her "helpful advice" was not only wrong, but also completely shunned. I then start to feel the atmosphere beginning to stifle in the classroom.
Some time passes by and I am now taking higher level math courses during the Winter Semester, but I occasionally go to the "Math Lab" to ask some questions about my homework. One day I get there, and guess who I see? Yep. Here I thought I was rid of her forever, but now she's back and still trying to get my attention. I sit down and start doing my work, trying hard to not look in her direction. She starts to talk out loud to the few people who are there. (She's does this to come off as an easy-going and approachable person). She also starts to talk loud enough so that anyone outside her immediate circle of friends will hear her and join in on the conversation.
Conclusion
So what am I doing/did? You ask.
(Winter Semester doesnt end until the end of March, 2011)
I just ignored them. To show that I wasn't interested in them back, I had to be very careful with how I came across through my body language. If I were to smile at them and say "Hey, hows it going?", they may have gotten the wrong idea about my intentions. I didn't want to even remotely come off as being interested in them, because I didn't want to lead them on in any way, and also because I didn't find them appealing. An easy way to get people off your back is to generally come off as an uninterested person, don't smile and don't laugh at anything, try to appear angry and irritable and people usually get the message.