Almost like magnetic pull. This happens to me with this guy I'm rather close friends with. For example, today we were standing next to each other but maybe 50-60 cm apart. I was extra careful not to move but I felt drawn to him. Eventually we did stand close so he could touch me with his elbow (and he did touch me). I know he moved closer to me since he was fidgeting all the time, but I was "fighting" hard not to move myself.