I realize the importance of boundaries and the tact necessary to enforce them in groups without killing the mood unless it gets REALLY bad. A while ago I remember I was in a group with a naturally self-confident dude with natural game where he was holding a flag for an event and I was so pumped up with everyone that I was going to try and help lift it higher by grabbing the top part he couldnt reach (he was short). It was a spur of the moment "lets goo" type thing. Looking back now, maybe it was an unintentional shit test on my part, but the way he reacted when I went to grab the flag was that he held onto it and did this shoulder roll while continuing what he was doing and acting like nothing happened. No facial reaction or words used. His actions made a statement though indirectly. I was literally like damn, not someone to fuck with.

What are other ways to tactfully indicate to someone to stop touching you or doing something using only non-verbals?