I'm going to say, "apparently the supermarket". Why? Because even though I've never had reason to think I have anything that comes to close to even resembling a magnetic personality, all I know is that when I'm there I seem to attract far more people into my personal space bubble than a lot of other people seem to. AND, I don't just have more incidents of one person invading my space bubble at the supermarket (and in the parking lot) than others seem to. I tend to attract whole little groups of people right into the very space where I am - no matter how otherwise unpopular that space might be.
I can go to where nobody else ever goes, only to discover that I'm apparently a leader of sorts; because almost immediately, I'll bring a crowd to where nobody ever goes otherwise. It's not just in the store either. It's on the sidewalk outside, the parking lot, the bottle-return, the Red Box - doesn't matter. I can bring people to the farthest, farthest, reaches at the far-end corner of the little mall by simply hiking way the hell over there and standing there for a minute and a half.
With years of this amazing ability to attract invaders to my space bubble and/or to anywhere I find where I think I may have a half a minute off somewhere, just to finish a coffee or straighten out my wallet; I have reached the only possible conclusion. That is, of course, that I am one, giant and powerful, magnet of a person who draws unsuspecting and innocent people into my perfectly modestly sized space bubble in a way that would otherwise defy the principles of magnetism. :/
So, as I said.... Supermarket, apparently.
(Watch out. I'll try not to exercise my magnetism over the Internet and cause you to be inextricably drawn to my local supermarket and space bubble, but I don't have a clue as to how it all works and therefore can't guarantee anything. All I know is that it one powerful case of magnetic personality I apparently have, and there's a good chance that I'm actually the cause of long lines and lack of parking spaces at the mall when I'm there. ) (Please imagine an eye-rolling emoticon here. Now please imagine a mean-face emoticon right next to it.)