I mean proper, crackling, sparky electric feeling - that you and the other person have agreed you definitely both felt physically?
A few years ago, I sat next to a male friend who I'd only ever thought of as a friend, during a meal out. We were a big group squashed around a table and our legs ended up pressed against one another and I am not kidding but it was like something had been switched on between us - well that's how it felt to me. Like a proper charge, just from this bit of contact. It went on all evening, fizzing and crackling away.
I was in a v happy relationship at the time so didn't want to initiate any conversation about it with friend. I am single now (as is he), and I would dearly like to ask him if I had imagined it or if he had felt it too, but really I would feel like a loon bringing this up, unless it's something that other people have experienced too, on both sides so at least I have an idea of whether this does happen to two people at the same time or if it was just all in my head!