Newbie here, coming from college setting.

Women read me as a shy, friendly guy. It's always the same: We have a great convo, the girl is deeply connected but she just sees me as a friend (The other month this one girl actually said "He is so cute, isn't he?" when introducing me to her friends. That was my wake-up call.).

I already applied some aspects (like body posture, eyes, the right way to smile, establishing dominance in the frame etc. etc.) and from the reactions I got I know I'm on a good way.

However I don't know how exactly to communicate the sexuality and naughtiness.

Example: Dormitory hallway, girl and me passing each other. Flirty looks. How to escalate from this point? Would be a good idea to compliment her on some piece of her clothing, pause for a sec, then physically close the distance and whisper some naughty line in her ear? If yes, how would that line sound, exactly?

DO NOT WHISPER something in a girls ear like that unless you are a lot further with your broads than you sound.

Your answer is the power of touching my friend. I come from the same quiet/shy background as yourself and the thing that will start getting the ladies to see you differently than a friend is by getting physical. Again DO NOT take this too far right away. You start small and move your way up just like you do when you are talking sexual. Start with High-5's and nudging(best when they say something dumb), then move onto hugs and touching hands. Can be whatever as long as you two are touching and getting close to one-another. bro fists, light punches, pokes, shoulder rub, whatever dude just be a touchy/feeling person, You know that feeling when a hot girl brushes your hand when she hands you your change, woman feel an amplified version of that from physical contact and we may think about you differently.
Besides that importance^ try also negging her, this can really get girls to see you being above her and that you do not care what others think. More attaction. As far as sexy goes mention dirty jokes and then slowly start moving sexual conversation towards them. Lighter versions I use involves topic of streaking and a story of how when I was younger I just walked around naked at school and did not give a fuck (the idea of either of you being naked is not a bad idea to get in her head). Hopefully something here helped GL

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PUSSY, MONEY, WEED.